Chapter 50: Assessment of Immune Function

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pg 1544 - 1559

What is the body's specific portective response to a foreign agent?

immunity

What functions are the body's defense mechanism against invasion and allows a rapid response to foreign substances in a specific manner?

immune system

What can result from immune system activation?

genetic and cellular responses

What factors affect the immune system?

CNS integrity, general physical and emotional status, medications, dietary patterns, stress of illness, trauma or surgery

What are two types of dysfunctions involving the immune system?

many genetically based, others acquired

What is a property of the immune system that provides protection against harmful microbes?

immune memory

What is the mechanism by which the immune system is programmed to eliminate foreign substances, but maintains ability to accept self antigens?

Tolerance

What is the concept of surveillance?

the immune system is in a perpetual state of vigilance, screening, and rejecting any invader that is recogned as foreign to the host

What is immunopathology?

study of diseases that result from dysfunctions within the immune system

Where might disorders from the immune system stem?

excesses or deficiences of immunocompetent cells, alterations in the function of these cells,
immunologic attack on self antigens
inappropriate or exaggerated responses to specific antigens

Where are the central and peripheral lymphoid organs, tissues and cells? (11 - head to toe)

-adenoids
-tonsil
-axillary lymph nodes
-thymus
-bronchus-associated lymphoid tissue
-spleen
-intestine
-Peyer's patches (ascending colon)
-Appendix
-Inguinal lymph nodes
-Bone marrow (B cells and T cells)
**They are also scattered throughout your upper abdomen & left clavicular area

What is autoimmunity?

normal protective immune response paradoxically turns against or attacks the body

What does autoimmunity lead to?

tissue damage

What is hypersensitivity?

Body produces exaggerated or inappropriate response to specific antigens

What are gammopathies?

Immunoglobulins are overproduced

What are primary immune deficiencies?

Deficiency results from improper development of immune cells or tissues
usually congential or inherited

What are secondary immune deficiencies?

Results from interference with an already developed immune system, usually acquired later in life

What do the different cells tyles of the immune system defend again?

infection and invasion by other organisms

What supports the immune system?

molecules responsible for the interactions, modulations, and regulation of the system

What are immunogenic epitopes?

antigenic determinants

Immune system molecules interact with immunogenic epitopes and do what?

present on foreign materials

After presenting what do these immune system molecule/epitopes interactions do?

initiate a series of actions in a host

What actions do epitopes initiate?

inflammatory response
lysis of microbial agents
disposal of foreign toxins

What are the major components of immune system?

central and peripheral organs, tissues and cells

Where are the WBC involved in immunity produced?

bone marrow

Lymphocytes (like other blood cells) are generated from what type of cells?

stem cells

What are stem cells?

undifferentiated cells

What are the two types of lymphocytes?

B lymphocytes (B cells)
T lymphocytes

Which WBC matures in the bone marrow and then enters circulation?

B lymphocytes

Where do T lymphocytes mature?

thymus (into several kinds of cells)

What red and white pulp organ acts somewhat like a filter?

spleen

What is the red pulp a site for?

old and injured RBCs destroyed

What does the white pulp contain?

lymphocytes

What connects the lymph nodes?

lymph channels and capillaries

Where are lymph nodes distributed?

throughout the body

What do lymph nodes do?

remove foreign material from the lymph system before it enters the blood stream
centers of immune cell proliferation

What is the basic function of the immune system?

remove foreign antigens to maintain homeostasis

What are some exampls of foreign antigens?

viruses and bacteria

What are the two general types of immunity?

natural (innate)
acquired (adaptive)

Which type of immunity is present at birth?

natural

Which types develops after birth?

acquired

Is natural immunity specific or nonspecific?

nonspecific

What does natural immunity provide?

a broad spectrum of defense against and resistance to infection

Following antigen exposure, what is natural immunity considered?

the first line of defense

Why is natural immunity considered the first line of defense?

protect the host with "remembering" prior contact with an infectious agent

How does the natural immune system co-coordinate the initial response to pathogens?

production of cytokines and other effector molecules

What do cytokines do? (2)

EITHER
(1) activate cells for control of the pathogen (by elimination)
(2) promote the development of the acquire immune response

What cells are involved in the acquired immune response? (7)

monocytes
macrophages
dendritic cells
natural killer cells
basophils
eosinophils
granulocytes

What are the two stages of the natural immune response mechanisms?

immediate (within 4 hrs)
delayed (b/t 4 and 96 hrs after exposure)

What is key to effective initiation of the immune response?

cellular response

What participates in both the natural and acquired immune responses?

WBCs

How do granulocytes fight invasion by foreign bodies?

releasing cell mediators - histamine, bradykinin, prostaglandins

What are the (3) types of granulocytes?

-neutrophils
-eosinophils
-basophils

Which are the first cells to arrive at the site where inflammation occurs?

Neutrophils

Which granulocytes increase in number during allergic reactions and stress responses?

eosinophils
basophils

What are the nongranular leukocytes?

monocytes
macrophages (histiocytes in tissue spaces)
lymphocytes

Which type of nongranular leukocytes functions as a phagocytic cell?

monocytes

What do phagocytic cells do?

engulf, ingest, destroy foreign bodies or toxins

Which destroys great numbers, monocytes or granulocytes?

monocytes

Which cells play major roles in humoral and cell-mediated immune responses?

lymphocytes (T and B cells)

Are there more T cells or B cells in the blood?

T cells (60-70%)

What is a major function of the natural immune system?

inflammatory response

What is elicited in response to tissue injury or invading organisms?

inflammatory response

How do chemical mediators assist in the inflammatory response? (5)

minimizing blood loss
walling off the invading organism
activating phagocytes
promoting formation of fibrous scar tissue and regeneration of injured tissue

What facilitates the inflammatory response?

physical and chemical barriers that are part of the human organism

What enhances activation of the natural immunity response?

processes inherent in physical and chemical barriers

What does physical surface barriers include?

intact skin
mucus membranes
cilia of the resp tract

What do physical surface barriers do?

prevent pathogens from gaining access to the body

What filter and clear pathogens from the upper resp tract?

cilia
coughing
sneezing

What are some chemical barriers of the natural immune response?

mucus
acidic gastric secretion
enzymes in tears, saliva
substances in sebaceous & sweat secretions

What do these chemical barriers do?

act in a nonspecific way to destroy invading bacteria and fungi

How are viruses countered?

"other means" - interferon

What does regulation of the immune response involve?

balance and counterbalance

How can dysfunction of the natural immune system occur?

when immune system components are inactivated or when they remain active long after their effects are beneficial

When is a person considered immocompromised or immunodeficient?

If an immune response fails to develop and clear an antigen sufficiently

What results if an immune system is overtly robust or misdirected?

allergies
asthma
autoimmune disease

What is the basis of many autoimmune disorders?

immune systems recognition of one's own tissues are "foreign" rather than as self

Which cells mediate the inflammatory response in microbial infections?

T cells
cytokines

How is the inflammatory response regulated?

cytokines
transformation of macrophage activation-inhibiting growth factor

What holds the promise of preventing graft rejection and aiding the body in eliminating cancerous or infected cells?

research on immunoregulation

When is acquired immunity acquired?

when pathogenic microbes resist natural immunity

How does acquired immunity usually develop?

prior exposure to antigen -
(1) immunization
(2) contracting a disease

How long after the exposure does the body produce an immune response sufficient to defend against reexposure?

weeks or months

What does acquire immunity rely on?

recognition of specific foreign antigens

What are the two mechanisms of the acquired immune response?

(1) cell-mediated response - T cell activation
(2) effector mechanisms - B cell maturation, antibodies

What are the two types of acquired immunity?

active -
passive

Which type of acquire immunity involves the immunologic defenses developed by the person's own body?

active

How long does active immunity last?

years or even a lifetime

What is a temporary immunity transmitted from a source outside the body?

passive immunity

What are examples of passive immunity?

immune globulin or immunity resulting from the transfer of antibodies from the mother to an infant in utero or through breast feeding

What do active and passive acquired immunity involve?

humoral & cellular immunologic responses

What are the body's three means of defense when under attack?

phagocytic immune response
humor or antibody immune response
cellular immune response

What is the first line of defence?

phagocytic immune response

What does the phagocytic immune response primarily involve?

WBCs (granulocytes & macrophages)

Which types of granulocytes are only weakly phagocytic?

eosinophils

Which type of cells also remove the body's own dying or dead cells?

phagocytes

What do dying cells in necrotic tissue release?

substances that trigger an inflammatory response

What is apoptosis?

programmed cell death

What is the body's way of destroying worn-out cells?

apoptosis

What is the second protect response?

humoral or antibody response

What does the humoral response begin with?

b lymphocytes

What can B cells transform themselves into?

plasma cells which become antibodies

What are antibodies?

highly specific proteins that are transported in the bloodstream
attempt to disable invaders

What is the third mechanism of defense?

cellular immune response

Which cells can turn into special cytotoxic (or killer) cells that can attack pathogens?

T cells (cytotoxic T cells)

What is the structural part of the invading or attacking organism that is responsible for stimulating antibody production?

antigen

Are all antigens naturally immunogenic?

No

Why would the body produce a number of antibodies in response to a single single bacterium?

The bacterium has a number of antigens on its surface

What happens once an antibody is produced?

it is released into the bloodstream and carried to the attacking organism

What does the antibody do once it "finds" the antigen?

combines with it
binding with it like a puzzle piece

What are the four well-defined stages in the immune response?

1. recognition
2. proliferation
3. response
4. effector

What is the initiating event in any immune response?

recognition of antigens as foreign by the immune system

What organs play the role of surveillors in the recognition process?

lymph nodes & lymphocytes

Where are lymph nodes distributed?

internally throughout the body, in the circulating blood, externally near the body's surface

What do the lymph nodes continuously discharge?

small lymphocytes

What is the continuous circuit of the lymphocytes?

blood > lymph nodes > blood > lymph nodes

What play an important role in helping the circulating lymphocytes process the antigens?

macrophages

Which immunity cells have receptors for antibodies and completment?

macrophages and neutrophils

What do macrophages and neutrophils coat microorganisms with to enhance phagocytosis?

antibodies, completement

What triggers the proliferation phase?

circulating lymphocytes containing antigenic messages return to nearest lymphocyte

What do the "sensitized" lymphocytes stimulate once in the node?

T & B lymphocytes to enlarge, divide, proliferate
T cell > cytotoxic T cells
B cell > produce and release antibodies

What does the response stage begin with?

the production of antibodies by the B lymphocytes in response to the specific antigen

What stimulates the resident lymphocytes to become cells that attack microbes directly?

cellular response

What are microbe-attacking transformed lymphocytes known as?

cytotoxic (killer) T cells

What type of antigens induce a cellular response?

viral (rather than bacterial)

What are the manifestations of the cellular response?

increasing number of lymphocytes

What is lymphocytosis?

increased T lymphocytes

When is lymphocytosis seen in the blood tests of patients?

viral illness
example: infectious mononucleosis

When does the humoral response predominate in the immune response?

bacterial pneumonias & sepsis

When does the cellular response predominate?

transplant rejection

Most immune responses to antigens involve which acquired responses?

both - humoral & cellular

What happens in the effector stage?

either the antibody of the humoral response or the cytotoxic T cell of the cellular response reaches and connects with the antigen on the surface of the foreign invader.

What characterizes the humoral response?

production or antibodies by B lymphocytes in response to a specific antigen

What is the role of the macrophages and the special T lymphocytes in the humoral immune response?

recognition

What are the ways in which B cells recognize and response to invading antigens?

1. directly triggering antibody formation
2. with T cell assistance. T cell returns antigenic material to nodes.

Why does a person who is repeatedly exposoed to the same antigen get an exaggerated and rapid immune response?

B lymphocyte clones with a memory for the antigen.
Memory Cells

What are antibodies?

large proteins
immunoglobulins

What are the subunits of antibodies?

light and heavy peptide chain held by disulfide bonds
each unit has a binding site for the antigen and complement system molecule.

How do antibodies defend against foreign invaders?

1. agglutination
2. opsonization
3. promote the inflammatory response

What are the combining sites of antibody molecules?

Fab fragments

What is agglutination?

cross-linking antigens causing them to bind or clump together
facilitates phagocytosis

What is opsonization?

antigen-antibody molecule is coated with a sticky substance
facilitates phagocytosis

How do antibodies promote the inflammatory response?

promoting the release of vasoactive substances
e.g. histamine, slow-reacting substances

What are the (5) different types of immunoglobulins the body can produce?

IgG - 75%
IgA - 15%
IgM - 10%
IgD - .2%
IgE - .004%

What are the major characteristics of IgG?

appears in serum & tissues
assumes a major role in bloodborne and tissue infections
activates the complement system
enhances phagocytosis
crosses the placenta

What are the major characteristics of IgA?

appear in body fluids
protects against resp, gi and gu infections
prevents absorption of antigens from food
passes to neonate in breast milk for protection

What are the major characteristics of IgM?

mostly in intravascular serum
first immunoglobulin produced in response to bacterial and viral infections
activates the complement system

What are the major characteristics of IgD?

Appears in small amounts in serum
possibly influences B-lymphocyte differentiation, but role is unclear

What is the characteristic of IgE?

appear in serum
takes part in allergic and some hypersensitivity reactions
combats parasitic infections

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