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Chapter 4 - The Immune System and Immunity

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What is inflammation?
An immediate response that occurs when foreign or injurious agents are allowed into the cells or tissues of the body
What are cells and chemical products produced during the inflammation process essential for?
Essential in activating another of the body's defenses, the immune system
What is the goal of the immune system?
To prevent foreign substances from entering the body and to establish immunity or resistance to disease-producing agents, such as bacteria and viruses, through the immune response
What is an antigen?
The agent that triggers the immune response
What can antigens be?
Chemicals, food proteins, products of microbes, microbes, abnormal human tissue, donor tissue cells, or the person's own normal tissue cells
What are usually large weight substances, such as proteins and polysaccharides?
Antigens
What are smaller weight substances, such as some metals, the oils from poison ivy leaf, and some medications such as penicillin, called?
Haptens
Haptens can only exhibit antigenic properties when combined with what?
A larger human protein from the skin, blood, or other tissue
What can trigger an immune response without the help of human protein?
Large molecular weight substances such as lipopolysaccharides
What does the immune system cells need to be able to distinguish between?
Self and non self
How does the body distinguish between self and non-self?
By coding each cell surface with molecules that are equivalent of an identification tag
What are molecular identification tags called?
Major histocompatibility complexes (MHC)
Where are MHC found?
On almost every cell that has a nucleus
What is another name for MHC?
Human leukocyte antigens (HLA)
What does MHC play an important role in?
Activating the immune response
What can cause the MHC of a particular cell to change?
Injury, viral infection, or other stimulus
What will MHC become when it changes?
MHC will become antigenic and the cell will no longer be recognized by the immune system as self
What happens when the cell is no longer recognized by the immune system as self?
Change initiates the immune response, which results in destruction of the cell
What plays a vital role in organ and tissue transplantation?
MHCs
What must be matched as closely as possible to minimize the potential for rejection of the transplant?
The MHC molecules of organ and tissue transplant recipients and their donors
What is nonspecific immunity?
Defense mechanisms that are nonspecific meaning they require no previous exposure to the offending agent to accomplish their objective of neutralizing that agent
What is another name for nonspecific immunity?
Innate immunity
What are examples of nonspecific immunity?
Physical barriers, chemical barriers, nonspecific phagocytes, indigenous microbes that compete with pathogens, inflammatory response, clotting system, and complement and kinin systems
What are included in physical barriers?
Integumentary system, skin and mucous membrane; Waldeyer's ring; nasal hairs and sneezing; respiratory tract cilia and coughing
What are included in chemical barriers?
pH of the skin; mucous secretions; gastric acids; tears, sweat, and saliva
What are included in nonspecific phagocytes?
Monocytes, macrophages, and neutrophils
What are an integral part of nonspecific immunity?
Inflammatory process, kinin, clotting, complement systems, and the actions of some of the phagocytic cells
What is essential in activating or enhancing the immune process that results in resistance to specific antigens or specific immunity?
Chemical mediators involved in or secreted by the phagocytic cells are essential in activating or enhancing the immune process
What are the two forms of immunity that helps maintain the body in a healthy state?
Nonspecific and specific immunity
What is another name for specific immunity?
Acquired immunity
How does specific immunity work?
Specific immunity acts against previously encountered agents with antibodies and activated lymphocytes that are specific for that agent
What is an immune response?
When specific immunity acts against previously enountered agents with antibodies and activated lymphocytes that are specific for that agent
How is the immune response carried out?
By the immune system
What does the immune system work in conjunction with?
The inflammatory and the healing and repair processes of the body to maintain the health of the individual
What are the principal organs of the immune system?
Bone marrow, thymus, spleen, lymphatic vessels and nodes, and mucosa associated lymphoid tissues
What does the bone marrow produce?
All of the cells of the immune system from precursor stem cells
What is the function of the thymus?
To educate some of these cells, called T cells, to make them self tolerant
What is self tolerance?
Having the ability to recognize the host's own cell as self
What are the functions of the spleen?
Serves as a filer to remove old and damaged red blood cells from the general circulation, and as part of the immune system; will mount an immune response against any foreign substance presented to it via the same circulating blood
What is the function of the lymphatic system?
Initiate an immune response , process some of the immune system cells, called B cells, and remove foreign substances from the host through a system of vessels and nodes placed throughout the body
What are numerous strategically placed mucosa associated lymph tissues important for?
Maintaining the immune status of the individual by detecting and removing injurious substances before they compromise this defensive barrier
Where are the mucosa associated lymph tissues located?
In the gastrointestinal, respiratory, and genitourinary tracts
What is the most notable lymph tissue?
Waldeyer's ring
Where is Waldeyer's ring located?
In the oral pharyngeal area
What is the Waldeyer's ring composed of?
The adenoid or pharyngeal tonsil and the lingual and palatine tonsils
What is the immune system consist of?
Chemical molecules and immune cells that inhabit lymphatic tissue and circulate in body fluids
What do the cells of the immune system include?
Macrophages and lymphocytes
What are lymphocytes?
White blood cells found in lymphoid tissues
What are the two categories of lymphocytes?
B lymphocytes and T lymphocytes
What is B lymphocytes most active in?
Humoral immunity
What is T lymphocytes most active in?
Cell mediated immunity, even though they are also necessary for the optimal functioning of humoral immunity
What are cytokines?
A complex system of chemical molecules
What produces cytokines?
Immune cells
What is the function of the cytokines?
Modulates and regulates how the system responds to a stimulus; various functions such as carrying messages to and from cells, enhancing cell growth, stimulating chemotaxis, and activating immune cells
What is the goal of the immune response?
To remove or neutralize antigenic substances
How does the immune response accomplish its goal to remove/neutralize antigenic substances?
System must recognize the "invader", react to the invader, and remember the invader
What are the two interactive components of the systemic immune system?
Humoral response and cell mediated cellular response
What is humoral immunity provided by?
B lymphocytes or B cells
Where are B cells developed?
In the bone marrow and then mature in lymphoid tissue throughout the body
What does the maturation process ensure?
The surface of each B cell contains an antibody
What is an antibody?
A molecule that will react against one or more specific types of antigen
What is the antigen-binding fragment (Fab)?
The part of the antibody that combines with or binds to an antigen
When does the B cell becomes activated?
When its antigen-binding fragment comes in contact with an antigen that it can bind to
What must bind to the B lymphocyte before it can become activated?
T helper cell
What is the end product of the B cell activation?
The transformation of the B cell into an antibody-secreting lymphocyte known as a plasma cell
Both B and T cells must function together before what happens?
A plasma cell can be created and antibodies porduced
How long do plasma cells live?
Only a few days
What does the process of B cell activation stimulate?
Stimulates the plasma cells to divide and become more numerous, which increases the amount of antibody produced
What is the bone marrow stimulated to produce?
More B cells that can become plasma cells upon activation
How long does it take to build up enough circulating antibody to inactivate most antigens after initial exposure?
About 2-3 weeks
What is the primary immune response?
The few weeks it takes for enough circulating antibody to inactivate most antigens after initial exposure
The slow production of antibody at the initial exposure results in what?
The host usually showing some overt signs and/or symptoms of the specific pathology or disease associated with that antigen
What is a memory B cell?
Another type of B lymphocyte
When is a memory B cell created?
As the primary immune response is terminated
Why do memory B cells carry the description of the antigen?
So that it will be recognized more quickly and acted against more rapidly the next time the antigen is encountered
If the host survives the primary encounter with the antigen, what will happen during the second exposure?
A second exposure will activate the memory B cells, which initiate an immediate, full immune response to the antigen
What is a secondary immune response?
When a second exposure will activate the memory B cells, which initiate an immediate, full immune response to the antigen
How long can memory cells live for?
Decades
What are memory cells ready to do?
To mount an immediate antibody assault when triggered by a "remembered" antigen
What are various ways in which antibodies attack circulating antigens?
1. Neutralize bacterial toxin
2. Bind with viruses to prevent entrance into cells
3. Cause the agglutination or clumping of antigens to facilitate phagocytosis
4. Bind to the surfaces of the antigen to aid in phagocytosis (opsonization)
5. Bind with an antigen to activate the complement system which then inactivate the antigen
What are the 5 major groups of antibodies or immunoglobulins?
IgG, IgM, IgA, IgE, IgD
What are immunoglobulins produced by?
The B lymphocytes
What is IgG?
Gamma globulin which is a circulating antibody and is directed against common infectious agents such as viruses, bacteria, and toxin
What does IgG bind to?
It binds to the antigen and then binds to a surface receptor on a phagocytic cell allowing for phagocytosis of the antigen-antibody complex
What allows for the phagocytosis of the antigen-antibody complex?
IgG binding to a surface receptor on a phagocytic cell
What does IgG activate?
The classic pathway of the complement system and is active in the secondary immune response
What is the only immunoglobulin that crosses the placental barrier and protects the developing child and newborn until his or her own immune system matures?
IgG
What makes up 80% of the circulating antibodies in the adult body?
IgG
How many types of IgG are there?
4
Where is IgM found?
On the surface of B cells
Which immunoglobulin is the largest of the immunoglobulins>
IgM
How many antigen-binding fragments can IgM have up to?
10 antigen binding fragments available for use
What is the first antibody produced in response to an antigen?
IgM
What is the main purpose of IgM?
To cause clumping or agglutination of antigen proteins during the primary immune response
What is agglutination?
Clumping
Which immunoglobulin is most efficient in activating the classic pathway of complement system?
IgM
Where is IgA found?
In secretions such as saliva, tears, and mucus of respiratory, gastrointestinal, and genitourinary tract
How many types of IgA are there?
2
What is IgA secreted by?
Plasma cells located in the epithelium of associated tissues
What do the secretions from plasma cells form?
Part of the primary defense mechanism of the body by preventing the attachment of the pathogens to epithelial ccells
What can IgA activate?
The alternative pathway of the complement system
What can be found in breast milk and can help protect the newborn infant?
IgA
What is IgE secreted by?
Plasma cells in the skin and mucous membrane
What does IgE trigger?
The release of histamine from mast cells and basophils and is important in the inflammatory response
Which immunoglobulin is responsible for the symptoms of immediate hypersensitivity allergic reactions
IgE
Which immunoglobulin helps protect the body from some parasitic infection?
IgE
What does an antigenic substance on the surface of the intestinal worms stimulate the release of?
Histamine from mast cells in the intestinal mucosa
What does histamine increase the permeability of?
Intestinal lining causing diarrhea, which is meant to result in expulsion of the worms
Where is IgD found?
On B lymphocytes cell surfaces
What immunoglobulin is associated with IgD?
IgM
What is the function of IgD?
It has regulatory effect on the functioning of the B cell
The humoral response uses what to accomplish its goal?
Antibodies
Antibodies in the humoral response cannot interact with what kind of cells?
Cells that have been infected with a virus or have become abnormal in any other way
What response can have antibodies interact with cells that have been infected with a virus or have become abnormal in any other way?
cellular or Cell mediated response
What is cell mediated immunity specific for?
Host cells (target cells) that have been infected with viruses or have been mutated and are possible sources of harm for the individual
What is the end result of cell mediated immune response?
Destruction of the target cell
What is another name for host cell?
Target cell
Cells involved in the cell mediated response are always what kind of cells?
Lymphocytes and include: T lymphocytes, natural killer cells, and macrophages
Where do T lymphocytes develop?
In the bone marrow from the same precursor or stem cells from which B lymphocytes developed
Where do the T lymphocytes mature (become self tolerant) and differentiate (become antigen specific)?
In the thymus
Where do B lymphocytes mature?
In lymphoid tissue
Where are T lymphocytes stored?
In lymphatic tissue all over the body
T cells must be what to function?
Activated
When does activation of T cells occur?
When an antigen presenting cell (APC) phagocytizes or otherwise binds to an antigen and brings it to the T cell
What are the most common antigen presenting cells?
Macrophages, monocytes, and B cells
What happens after the APC presents its antigen to the T cell?
The T cell is activated against that antigen
What cytokines assists in the activation of the T cells?
Interleukins
What does the activation of T cells stimulate?
Stimulates the T cell to divide and produce several types of T lymphocytes that are specific for the activating antigen
T cells that can live for long periods of time and maintain their antigenic specificity become what?
T memory cells
What determines the T cell functions?
Protein molecules carried on the T cell surfaces, which are called clusters of differentiation
What are clusters of differentiation?
Protein molecules carried on the T cell surfaces
What cluster designations of T cells are significant?
CD4+ (T helper cell) and CD8+ (T cytotoxic cell)
What do T helper cells regulate?
The action of all the other cells of the immune system
What do T helper cells increase or enable the functioning of?
B lymphocytes, macrophages, natural killer cells, and other T cells by the release of cytokine
Humans normally have twice as many what cells circulating in the blood as what cells?
Twice as many T helper cells compared to T cytotoxic cells
What is another name for T helper cells?
CD4+
What is another name for T cytotoxic cell?
CD8+
What are T cytotoxic cells able to do with cells that have been recognized as being antigenic?
T cytotoxic cells are able to kill cells that have been recognized as antigenic
What are examples of antigenic cells?
Cells infected with viruses, cancer cells, and sometimes normal cells that the body has confused as nonself
What activated cytotoxic cell?
A T helper cell or macrophage before it can bind to and destroy the antigen
Where are cytotoxic cells active?
In tissue and organ rejection
What are natural killer (NK) cells similar to?
Cytotoxic T lymphocytes
What is the difference between cytotoxic T lymphocytes and natural killer cells?
Natural killer cells do not need to sensitized to an antigen before reacting with that antigen; they have the ability to recognize foreign substances without any input from other cells or chemical mediators
What do NK cells do once they recognize virus infected cells and other abnormal cells?
destroys them
Nk cells can do what in the presence of foreign substances?
Respond immediately thus important role in immune system
Often NK cell functions are impaired in what?
Immune deficiency disorders such as AIDS
There is evidence that what plays an important role ind detecting and eliminating what?
cancer cells before they can multiply
What do macrophages provide a crucial cellular link to?
inflammatory process and the immune system response
What are macrophages?
Monocytes that have left the circulating blood to enter connective or other tissues where they develop into macrophages
What are histiocytes?
Macrophages found in connective tissue
What are Kupffer cells?
Macrophages found in the liver
What are Langerhans cells?
Macrophages found in the epidermis
Do macrophages have to be sensitized by an antigen to recognize and destroy it?
no
What do the receptors on the surface of the macrophage recognize?
Opsonized matter
What can macrophages be activated to become more?
More destructive by chemical mediators released by CD4+ T cells
What are activated macrophages able to do?
Secrete many more chemical mediators and have enhanced capabilities related to chemotaxis, phagocytosis, and antigen presentation; exhibits increased metabolism, size and ability to adhere to, and speard on surfaces
When higher level of destruction is no longer necessary, what happens to the macrophages?
Chemical mediators are released that deactivate the macrophages
After macrophage destroys the antigen it will present specific proteins from it to a T lymphocytes, therefore activating what?
Lymphocyte and starting the immune response
Macrophages can survive for years, but why do they have to be reactivated when they encounter the same antigen again?
Because they retain no memory of an antigen after it has been destroyed
What does the cell mediated immune response results in?
Destruction of the target cells and or activation of the humoral immune response
What are two forms of specific immunity?
Active and passive
When does active immunity occur?
When antibodies are produced by the body in response to an antigen
Does active immunity occur naturally or artificially?
Both; naturally by an individual having an infectious disease (chicken pox) and artificially through vaccinations
What are vaccines produced with?
Either killed or attenuated (weakened) bacteria or virus or chemically altered toxins
Why does active immunity produce long term immunity?
Because the memory cells that are produced in response to the antigen will reproduce for life of the host
Why are booster shots given?
To make sure that the memory stays strong and to strengthen the antibody response
When does passive immunity occur?
When the host does not form his or her own antibodies but is given antibodies derived from another source, human or animal
Why is passive immunity short lived?
Because there is no memory produced in the individual's own immune system; no B cells are activated by antigens to produce plasma or memory cells
Passive immunity occurs naturally prior to what?
Prior to birth when maternal antibodies are transferred across the placenta to the infant
Passive immunity also occurs when individuals are given what?
An injection of specific antibodies from a second source, very often a horse
What is the immunoglobulin used most often for vaccinations?
Gamma globulin (IgG)
What is an example of gamma globulin used as a vaccination?
Gamma globulin is given to unvaccinated dental healthcare workers who have a needlestick injury or percutaneous exposure to the hepatitis B virus, as a form of postexposure prophylaxis to try to boost the immune response against any viral particles that may have entered the body
Dysfunction of the immune system can be grouped into what three major categories?
Hypersensitivity reactions, autoimmune diseases, and immune deficiency disease
What do hypersensitivity reactions set the immune system against?
The host and in many case become destructive to the individual
When does hypersensitivity occur?
When the body's cells come into contact with something they dislike
How many types of hypersensitivity reactions are there?
4
What are the first three types of hypersensitivity?
Immediate responses and are mediated or controlled by antibodies
What is the fourth type of hypersensitivity?
A delayed reaction and is mediated or controlled by a cellular response
What are the four types of hypersensitivity?
Type I (anaphylactic or atopic reactions), Type II (cytotoxic reactions), Type III (immune complex mediated reactions), and Type IV (Cell mediated or delayed hypersensitivity reactions)
When does Type I reactions occur?
Immediately (within minutes) after exposure to a previously encountered antigen
What are the two major forms of Type I reaction?
Systemic or anaphylactic reactions and atopic reactions that include skin reactions, asthma, and upper respiratory manifestations
Which form of Type I reaction causes the most dramatic reactions?
anaphylactic because they are life threatening for those affected by them
Individuals with anaphylactic reactions must do what?
Be on constant alert so they do not come into contact with substances they are allergic to
In the systemic form, plasma cells produce what to respond to a particular antigen?
IgE
What does IgE do during the systemic form of Type I reactions?
Attaches to the surface of mast cells throughout the body
What happens when mast cells encounter a specific antigen again?
They release granules that contain histamine, which results in dilation and increased permeability of the blood vessels
What signs appear as a result of mast cells encountering a specific antigen?
Blood pressure falls, entire circulatory system may shut down, breathing impaired
Why is breathing impaired during the systemic form of Type I reactions?
Because histamine causes constriction of smooth muscles in the bronchioles and tissue edema
What do individuals wear if they have known allergies especially to certain drugs and latex?
Medical identification tags
What is the most effective treatment for anaphylatic reaction?
Injected epinephrine
What is the action of epinephrine?
Causes constriction of dilated blood vessels, which increases blood pressure and causes relaxation of the smooth muscles in the lungs, opening airways,
individuals who have severe anaphylactic reactions carry what?
Epi pen
What does the epi-pen contain?
A single dose of epinephrine that is easily injected by even young children
What is atopic form of Type I reactions exemplified by?
Hay fever and mold and animal allergies
What do the symptoms of the atopic form of Type I reactions depend on?
Where the antigen comes into contact with the body
What will happen if antigens of the atopic form of Type I comes in contact with the skin?
Hives or urticaria will appear
When will hay fever be evident?
If contact is made in the upper respiratory system
When will asthma be evident?
If contact is made with lungs
How are localized reactions treated?
With drugs that control or inhibit the releasse of histamine (antihistamine) or act on other elements of the immune response such as the release of leukotrienes or cytokines
When do cytotoxic reactions occur?
When an antibody, usually IgG or IgM, combines with an antigen that is bound to the surface of cells of a specific type
What can cytotoxic reactions result in?
1. Direct lysis or destruction of the affected cells
2. Prepare affected cells for phagocytosis by immune system cells
3. Cause the affected cells to malfunction in some way
What is a classic example of direct lysis?
A transfusion reaction that occurs when an individual is given an incompatible blood type
What type of reaction is erythroblastosis fetalis?
Cytotoxic reaction
when does erythroblastosis fetalis occur?
During second pregnancy with an Rh+ fetus, since it takes an initial sensitizing exposure or first pregnancy with an Rh+ fetus to enable hypersensitivity reaction
What happens during erythroblastosis fetalis/
Maternal antibodies against the positive factor cross the placental barrier and destroy the red blood cells of the fetus, necessitating an immediate blood transfusion when infant is born
How is erythroblastosis fetalis avoided?
If at risk mother is identified before birth of first child and is given injections of gamma globulin containing Rh antibody
What will the Rh antibody prevent?
The sensitization of the mother and this will prevent problem with a future pregnancy
Hyperthyroidism is an example of what reaction?
Cytotoxic reaction in which the cells remain viable but malfunction and cause excess production of thyroid hormones
What resultswhen something happens that changes the major histocompatibility complexes attached to some of the body's cells?
The immune system thinks the affected cells are foreign and attacks them
If a problem is related to drug or known environmental agent, what should be done to stop the hypersensitivity reaction and the resulting damage?
removal of the offending agent should stop the reaction
If a cause is unknown, what is the problem considered?
Autoimmune dysfunction
In immune complex mediated reactions, what immunoglobulins form antigen antibody complexes with circulating antifens?
IgN, IgA, and IgG
What can antigens be characterized as?
Exogenous such as bacteria, viruses, drugs, or chemicals; or endogenous such as created by the body as part of the immune dysfunction
When is the damage to tissues done in the hypersensitivity?
When antigen antibody complexes are deposited in a particular part of the body and cause the initiation of the inflammatory response
What do the chemotactic agents that are released in the inflammatory repsonse cause PMNs to do?
Causes PMNs to travel to the site or sites and release their destructive enzymes
Enzymes can cause what kind of destruction?
Systemic or localized tissue destruction
What are examples of autoimmune reactions?
systemic lupus erythematosus, rheumatoid arthritis, and forms of glomerulonephritis (kidney disease)
What do cell mediated reactions involve?
Specific T cells that have been sensitized to a particular antigen; do not require action of antibodies
Type Iv reactions can take up to how long before full response is observed?
24-72 hours
What is contact dermatitis?
An example of one of the most common forms of type IV hypersensitivity
What are haptens?
Very small antigenic substances
What happens when haptens combine with skin proteins?
result in a hypersensitivity reaction that will not stop until the antigen is eliminated or the skin is destroyed
What are examples of haptens?
Poison ivy and sumac leaves and certain chemicals in rubbers
What is type IV hypersensitivity resulting in?
T lymphocytes reacting with an antigen, causing death of the involved cells or initiation of an inflammatory response
Substances that can cause a contact allergic reaction are what?
Poison ivy, metals, cosmetics, and various chemicals, including those used in toothpaste and mouth rinse
What can help alleviate the symptoms associated with cutaneous rashes?
topical corticosteroids and antiitch crea,
What are used to treat more severe reactions?
Systemic corticosteroids
What is graft versus host or host versus graft reaction?
A type IV hypersensitivity reaction where the tissue and organ reject the graft
What is graft versus host reaction a result from?
results from an immune response to major histocompatibility complexes that re present on the surface of the cells in the donor or recipient tissue
Are MHCs identical?
With the exception of identical twins, no matter how closely the MHCs matched, they are not identical
What is Sjogren syndrome?
A type IV hypersensitivity reaction the results in salivary and other exocrine gland damage caused directly by T and B lymphocytes
What does the immune system usually functions under the premise of?
Self tolerance
What happens when the immune system loses the ability to distinguish self from nonself or there is an alternation of the host's cells that changes their makeup?
The immune system will attack the cells of the host just as if they were foreign matter and an autoimmune disease becomes manifest
Tissue damage that is done in these diseases is the direct result of what?
The actions of the host's own immune and inflammatory responses
What are autoimmune diseases usually?
Chronic conditions that manifest with many exacerbations and remissions often over many years
What do most autoimmune diseases present or manifest itself as?
Type II, type III, or Type IV hypersensitivity reactions
Do autoimmune diseases have a genetic predisposition?
Yes
What are examples of conditions that have their basis in an immune system that is overstepping its boundaries?
Hypersensitivity reactions and autoimmune disorders
When does immune deficiencies occur?
When the immune system or part of it fails to function
What are two basic categories of immunodeficiency diseases?
Primary (congenital) and secondary (acquired)
What are primary immunodeficiency diseases caused by?
Genetic or congenital abnormality
What is congenital defined as?
Existing at time of birth
What are congenital abnormalities caused by?
May result from a spontaneous genetic mutation or a random developmental defect not necessarily caused by an inherited trait
What do congenital abnormalities result in?
defective functioning of at least one part of the individual's immune system or inflammatory process; impaired ability of host to fight off infection and maintain health status of body
What is Bruton's disease?
The individual's B cells do not mature correctly and do not produce functioning antibodies
Recurrent bacterial and some viral infections begin to cause problems in Bruton's disease at about 6 months of age which corresponds with what?
to the time when maternal antibodies are depleted
A child with Bruton's disease has T cells that function normally so antigens such as most viruses and fungal infection that are normally destroyed through T cell function are still what?
destroyed
How is Bruton's disease treated?
With injections of immunoglobulins, and most of its victims survive through adulthood
What is DiGeorge syndrome?
A genetic disorder that can be inherited or can result from a spontaneous genetic mutation that occurs in the developing fetus
What are the problems created with DiGeorge syndrome caused by?
Failure of the third and fourth pharyngeal pouches to develop
What is the result of DiGeorge syndrome?
Thymus, parathyroid glands, and some of the thyroid gland are partially or totally missing; and the face, ears, and mouth may be formed incorrectly; individual may be mentally challenged
What does DiGeorge syndrome affect?
The T cells and B cells
How are T cells affected by DiGeorge syndrome?
T cell level is diminished or altogether absent, making individuals more susceptible to viral and fungal infections
How are B cells affected by DiGeorge syndrome?
B cell activity, including production of antibodies, is also diminished because B cells must be activated with the help of CD4+ T helper cells
What must the dental hygienist remember in all instances of immune deficiency?
Normal standard precautions for preventing the transmission of disease may not be effective and that any contact with pathogenic organism may cause a fatal infection
When does acquired or secondary immunodeficinecy diseases develop?
Develop after birth and no related to genetics
What conditions can be associated with acquired immune deficiency?
renal disease, cancer, malnutrition, diabetes, immunosuppressive drugs (corticosteroids) or treatments (radiation), advanced age, tuberculosis, HIV infection and more
What is one of the most common causes of immune suppression?
The use of corticosteroid drug therapy to control the myriad of inflammatory diseases that are found today
What is the action of corticosteroids?
Depress the inflammatory response, thereby reducing the damage and symptoms associated with diseases such as rheumatoid arthritis and systemic lupus erythematosus
What do immune deficiency conditions allow for?
Opportunistic infections to overwhelm the host
What are opportunistic infections caused by?
Organisms that usually pose no threat to the individual with a normal immune system
Why are individuals undergoing chemotherapy for cancer at higher risk of outgrowth of oral Candida albicans?
Because their immune systems are not able to control this normally innocuous microorganisms that lives with us at a commensal relationship
What is commensal?
Causing neither harm nor benefit
A compromised individual is also at risk of having infections such as what?
periodontal disease become more aggressive and severe than they would be in an individual with a normal immune system
What is the most prominent immune deficiency disorder?
AIDS