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Midterm 3: Innate and Adaptive Immunology

Terms in this set (225)

Innate immune system
Immediate, non-specific immunity
No learning process or memory
Adaptive Immunity
Acquired specific immunity
Specific recognition and memory
First-line defenses ___
Block entry through inside borders and outside borders: physical, chemical and biological barriers
Tears ___
Wash away irrational substances and microbes
Lysozyme kills many bacteria
The skin provides ___
A physical barrier to the entrance of microbes
Acidic pH discourages the growth of organisms
Sweat, oil, and fatty acid secretions kill many bacteria
In the large intestines ___
Normal normal bacterial inhabitants keep invaders in check
Saliva
Washes microbes from the teeth and mucous membranes of the mouth
The respiratory tract uses ___
Mucus to trap organisms
Cilia to sweep away trapped organisms
The stomach uses ___
Acid to kill organism
What are the main first line defenses?
The skin, mucous membranes, antimicrobial substances, and normal flora
The skin makes it ___
Difficult for microbes to penetrate, and acts as a chemical and physical barrier
The epidermis is ___
The outer most layer of the skin and consists of tightly packed layers of epithelial cells.
The dead skin cells are water repellent due to them being filled with keratin
The outermost layer of the skin consists of cells filled with ___
The protein keratin which creates an orangish appearance and hydrophobic environment
The dermis is the ___
Connective tissue layer beneath the epidermis where sweat glands and sebaceous glands are located
Sweat is produced by ___
Sweat glands
Sebum is produced by ___
Sebaceous glands
Moist skin leads to ___
Higher skin infections (ex: fungal athletes foot)
The mucous membrane is an example of ___
Inside borders
The epithelial layer is bathed in ___
Mucus and lines the digestive, respiratory, and genitourinary tracts
Mucous is used to ___
Moisten tracts while also trapping & washing off pathogens using the ciliary escalator and peristalsis
The ciliary escalator refers to the ___
Beat action of cilia that propels microbes upwards away from the lungs
Peristalsis refers to the ___
Muscular contraction of the intestinal wall which results in the movement of content into the rectum for defecation
Sebum/cerulean (on the skin/in the ear) are used ___
As a chemical barrier because they're rich in fatty acids which causes them to have a low pH
Acid kills most bacteria and toxins, except ___
Clostridium botulinum toxin
Lactoferrin is used as a ___
Chemical barrier because it binds iron so microbes can't utilize it
AMPS are a broad spectrum of ___
Antimicrobial peptides produced by our cells (ex: defensins and lysozyme)
Defensins works as an antimicrobial peptide because it ___
Forms pores in microbial membranes which leads to cytolysis
Lysozyme works as an antimicrobial peptide because it ___
Degrades prostaglandins
Normal flora acts as a ___
Biological barrier because it uses microorganisms that colonize body surfaces in healthy humans to prevent the overgrowth of harmful microbes by competitive exclusion and the production of toxic compounds (toxic to various microbes not so much humans)
Competitive exclusion of pathogens, utilized by the normal flora, works by ___
Covering binding/attachment sites and consuming available nutrients; extremely effective against Salmonella and Shigella
The production of toxic compounds, utilized by the normal flora, works by ___
The fermentation of products (ex: acetic and butyric acids) which inhibit intestinal pathogens (esp. Salmonella)
Lactobacillus produces lactic acid in the vagina (which lowers the pH) and hydrogen peroxide (esp. effective against Chlamydia, Candida albicans)
What are the categories of purpose for blood cells?
Transportation, regulation or hemostasis, and protection
Hematopoietic stem cells lead to ___
Progenitor stem cells which are either Myeloid and Lymphoid stem cells
Myeloid stem cells can give rise to ___
Erythrocytes (RBCs), Megakaryocytes, Mast cells, Eosinophils, Basophils, Neutrophils, or Monocytes
Megakaryocytes can become ___
Platelets (thrombocytes)
Monocytes can become ___
Dendritic cells or macrophages
Lymphoid stem cells can become ___
Any of the lymphocytes which are T-cells, B-cells, or NK cells
What are the different types of leukocytes (WBCs)?
Granular and Agranular leukocytes
WBC counts measure ___
Leukocytes in the blood
Leukocytes coordinate efforts in controlling infections in the ___
Second and third lines of defenses
A high or low WBC can indicate ___
Infection, autoimmune disease, cancer, side-effects to medication/treatment or other medical conditions
Blood cells originate from hematopoietic stem cells in the ___
Bone marrow in a process called hematopoiesis
Blood cells are ___
Always found in normal blood (numbers change during infections tho)
Move around the body using the circulatory system
Can move against the flow of blood or lymph to reach infection sites
Can move through walls of capillaries to enter infected tissues
Some reside in specific tissues
What are the general cell categories from hematopoiesis?
RBC, platelets (thrombocytes), and WBCs
Granular leukocytes are named based on ___
Staining properties of their granules
Granulocytes include ___
Mast cells, Eosinophils, Basophils, and Neutrophils
Neutrophils (Polymorphs) (stain poorly; a pale lilac) are the most numerous of the WBCs, making up roughly 60% of blood WBCs. They're ___
Important in inflammation because they're the first responders using diapedesis
Intracellular killing is done by Phagocytosis
Extracellar killing is done by Degranulation or NET (Neutrophil extracellular traps) release in a process called NETosis
Extracellular killing can be done by using ___
Reactive oxygen species (ROS) and/or Neutrophil extracellular traps (NETs)
Basophils are strained blue w/ basic dye, they're involved in ___
Allergic rxns and inflammation. They release heparin, histamine, and cytokines.
Similar in appearance and function to Mast cells, found in tissues instead
Eosinophils are stained orange-red w/ acidic dyes, they're involved in ___
Allergic rxns, inflammation and combatting parities via the ADCC. They're found mostly in specific tissues (but not in the lungs)
Agranulocytes are leukocytes with their granules ___
Not visible w/ light microscope after staining
Monocytes (mononuclear phagocytes) circulate in the blood and migrate into tissues to differentiate into ___
Macrophages or Dendritic cells which are both antigen-presenting cells (APCs) that act as sentinel (scouts) phagocytic cells
NK cells are sentinel cells that target ___
Infected body cells, tumor cells and parasites by releasing toxic substances (performing and granzymes)
T and B cells are ___
Highly specific and play key roles in adaptive immunity
In APCs (Antigen-Presenting Cells), step 1 consists of ___
A bacterium is engulfed by phagocytosis into a dendritic cell and is encased in a phagosome
In APCs (Antigen-Presenting Cells), step 2 consists of ___
Lysosomes fuse w/ the phagosome and digest the bacterium
In APCs (Antigen-Presenting Cells), step 3 consists of ___
Immunodominant epitomes are associated w/ MHC II and presented on the cell surface
Cytokines are responsible for cell communication which means they ___
Act as a "voice" of cells allowing a coordinated immune response
Regulate timing, intensity, duration of immune response
And are produced mostly by immune cells
What are the major categories of cytokines?
Chemokines, Interferons (IFNs), Colony-Stimulating Factors (CSFs), and Interleukins (ILs)
Chemokines are responsible for ___
Chemotaxis of leukocytes
Interferons (IFNs) are ___
Produced in response to viruses. They alert neighboring host cells, stimulate NK cells, and macrophages
Colony-Stimulating Factors (CSFs) ___
Induce hematopoiesis
Interleukins (ILs) activate ___
Immune cells proliferation, maturation, activation, and migration during immune responses
Pathogen-Associated Molecular Patterns (PAMPs) are microbial components that remained unchanged over the course of evolution, they include ___. They're molecules present on pathogens and not self.
Cell-wall components (LPS, PG), bacterial peptides (flagellin), and bacterial and viral DNA or RNA
PAMPs can be detected as "non-self" by PRRs of ___
Sentinel cells of the innate immune system, triggering a response against a pathogen
Pattern-Recognition Receptors (PRRs) are receptors of sentinel cells that can detect PAMPs and trigger a response against pathogen such as ___
Phagocytosis
Releasing cytokines to alert and recruit immune cells, and trigger inflammation
What are the major types of PRRs?
Toll-Like Receptors (TLRs)
RIG-Like Receptors (RLRs)
NOD-Like Receptors (NLRs)
TLRs are ___
Membrane-bound and monitor a cell's surroundings
RLRs and NLRs are ___
Soluble and monitor a cell's cytoplasm
The Complement System which consists of a group of serum proteins (C1-C9, Factors) can ___
Detect pathogenic components, and activate a cascade of events leading to opsonization, inflammation, and cytolysis
Phagocytosis is the ___
Ingestion (endocytosis) of microbes by phagocytes (ex: neutrophils, fixed/free macrophages, dendritic cells)
Inflammation is the body's response to ___
Tissue damage and infection to help contain the site of damage, localize response, eliminate invader, and restore tissue function
Fever is an ___
Abnormally high body temp in response to infection caused by pyrogens (either endogenous or exogenous)
The second line of defense includes the ___
Complement system, phagocytosis, inflammatory responses, and fever
The alternative pathways is triggered by ___
Factors which bind to microbial invaders
The lectin pathway is triggered by ___
Mannose-binding lectin (MBL) binding to microbial invaders
The classical pathway is triggered by ___
Antibodies binding to microbial invaders
All three pathways (Alternative, Lectin, and Classical) are all activated by the ___
Formation of C3 convertase
In all three pathways (Alternative, Lectin, and Classical), C3 convertase splits ___
C3 into C3a and C3b
In all three pathways (Alternative, Lectin, and Classical), C3a ___
Combines with C5a to induce an inflammatory response by inducing changes that contribute to local vascular permeability and attract phagocytes
In all three pathways (Alternative, Lectin, and Classical), C3b can ___
Bind to microbial cells and function as an opsonin or combine with other complement proteins to form C5 convertase
In all three pathways (Alternative, Lectin, and Classical), C5a ___
Combines with C3a to induce an inflammatory response and acts as a chemoattractant
In all three pathways (Alternative, Lectin, and Classical), C5b ___
Combines with complement proteins C6, C7, C8, and C9 to form membrane attack complexes (MAC complexes) that insert into cell membranes and induce lysis of foreign cells
The Complement System ___
Functions as a sensor system and a second line defense through the complement proteins (C1-C9 + factors) activated by being split (a and b).
Complements/Enhances activities of adaptive immune system through the classic pathway
Each of the 3 pathways (Alternative, Lectin, and Classical) all include ___
A detection step, activation of C3 and C5
An inflammatory response induced by C3a and C5a
Opsonization by C3b (or lectin) which leads to phagocytosis
Cytolysis which leads to lysis of foreign cells by the membrane attack complexes (MAC complexes) which are formed by C5b, C6, C7, C8, and C9
In the Alternative pathway activation, C3 convertase is formed when ___
Components of the microbe's membrane combine with BDP to split C3 into C3a and C3b
In the Lectin pathway activation, C3 convertase is formed when ___
Mannose-binding lectin (MBL) binds to the microbial invader and then is converted into C2 and C4. Similarly to the Classic pathway, C2 and C4 are then split into C2b, C2a, C4b, and C4a. C2a and C4b are responsible for splitting C3 into C3a and C3b
In the Classical pathway activation, C3 convertase is formed when ___
Antibodies bing to the microbial invaders and split C1 into C2 and C4. Similarly to the Lectin pathway, C2 and C4 are then split into C2b, C2a, C4b, and C4a. C2a and C4b are responsible for splitting C3 into C3a and C3b
In summary, in the Classical pathway, ___
BDP is the C3 convertase that splits C3 into C3a and C3b
In summary, in the Lectin and the Classical pathways, ___
C2a and C4b is the C3 convertase that splits C3 into C3q and C3b
C5a is the ___
Most potent pro-inflammatory mediator
The first step in phagocytosis is ___
Chemotaxis (by chemoattractants such as C5a )and adherence (either directly or indirectly) of the phagocyte to the microbe
The second step in phagocytosis is ___
Ingestion of the microbe by the phagocyte
The third step in phagocytosis is ___
Formation of a phagosome (phagocytic vesicle)
The fourth step in phagocytosis is ___
Fusion of the phagosome with a lysosome to form a phagolysosome
The fifth step in phagocytosis is ___
Digestion of the ingested microbes by enzymes in the phagolysosome
The sixth step in phagocytosis is ___
Formation of the residual body containing indigestible material
The seventh step in phagocytosis is ___
Discharge (exocytosis) of the waste material and antigen presentation on Major Histocompatibility Complex (MHC)
In Direct adherence, ___
PAMPs binding to receptors (TLRs) initiates phagocytosis and induces the phagocyte to release specific cytokines to recruit additional phagocytes to help
In Indirect adherence,
Host molecules opsonizing pathogens bind to receptors to initiate phagocytosis
The Inflammatory Response is a ___
Proactive biological response triggered by inflammatory mediators released by host cells (e.g., cytokines, histamine, PGs) in response to tissue damage or infection.
Help contain the site of damage, localize response, eliminate invader, and restore tissue function.
Results in pain (chemicals, nerve), swelling (edema; fluids), redness (erythema; vasodilation), head (vasodilation), sometimes loss of function (in severe cases)
Can be acute or chronic
The Inflammatory Response is initiated by tissue damage, but the first rxn to that damage consists of ___
Chemicals being released by fixed macrophages, mast cells, damaged cells (cytokines, histamine, heparin, and PGs)
The Inflammatory Response is initiated by tissue damage, but the second rxn to that damage consists of ___
Vasodilation
The Inflammatory Response is initiated by tissue damage, but the third rxn to that damage consists of ___
Increased permeability of blood vessels
The Inflammatory Response is initiated by tissue damage, but the fourth rxn to that damage consists of ___
Margination
The Inflammatory Response is initiated by tissue damage, but the fifth rxn to that damage consists of ___
Diapedesis
The Inflammatory Response is initiated by tissue damage, but the sixth rxn to that damage consists of ___
Phagocytosis
The Inflammatory Response is initiated by tissue damage, but the last rxn to that damage consists of ___
Tissue repair
The Hypothalamus, temp-regulation center, is normally set at 37 degrees C (98.6 degrees F), but during infection in response to ___
Pyrogens, it raises
Endogenous pyrogen examples ___
Cytokines (interleukins) and C5a
Exogenous pyrogen examples ___
LPS of Gram negative bacteria
A moderate temperature rise ___
Increases the rate of enzymes, enhances the inflammatory response, phagocytic killing, multiplication of lymphocytes, the production of interferons and antibodies, and the release of leukocytes from bone marrow
A high temperature rise ___
May compromise older people with medical conditions, can cause dehydration, seizures in children, delirium and coma. Death occurs when body temperature reach 45 degrees C (113 degrees F)
What is the adaptive immune system?
A specific recognition and memory defense that is acquired through infections or vaccination
The third-line of defense ___
Destroys invaders and memorizes the response
Designed to recognize self vs. non-self
Dual: Humoral and cellular immunity
Primary vs. Secondary responses
What are the two main types of cells in the adaptive immune system?
B and T cells
Antigens are molecules that are used to identify ___
Self or non-self components
Self-antigens can elicit an immune response in others in situations like ___
Transplants or transfusions
Non-self antigens are immunogens that elicits an immune response in situations like ___
Microbes, vaccines, or pollen
Non-self antigens are immunogens that elicit the production of ___. They can be recognized by our receptors
Highly specific corresponding antibodies
Epitopes are ___
Antigenic determinants.
Stretches of AA/3D regions o antigen
Recognized by specific receptors
Bacterial cells have multiple different versions
Each antibody specifically binds to ___
One corresponding epitope
Immature lymphocytes lack fully ___. While Mature Naive lymphocytes have fully developed versions
Developed antigen-specific receptors and self-tolerance
Activated lymphocytes are antigen-bound and proliferate to the ___
Effector lymphocytes and memory lymphocytes
Immature lymphocytes become mature naive lymphocytes through___
Maturation
Mature naive lymphocytes become activated lymphocytes through ___
Activation
Effector lymphocytes are descendants of activated lymphocytes that ___
Mount an immune response against a current infection (ex: plasma B cells, TC cells, and TH cells)
Memory lymphocytes are long-lived descendants of activated lymphocytes and are responsible for a ___
Rapid secondary response if an antigen is ever encountered again
B lymphocytes (B cells) are responsible for a ___
Humoral immune response
B lymphocytes (B cells) form and mature in ___
Bone marrow. Maturation involves maturation of BCRs and negative selection (removing) of self-reactive B cells
Each B cell expresses several B-cell receptors (BCRs) all with ___
2 binding sits that recognize the same specific epitope on pathogens. (More than 100 million in our body)
B lymphocytes (B cells) travel to lymphoid tissue (such as the spleen or lymph nodes) as ___
Naive B cells that are activated by recognizing matching extracellular antigens
T lymphocytes (T cells) are responsible for a ___
Cell-Mediated immune response
T lymphocytes (T cells) are formed in the ___
Bone marrow and mature in the thymus into helper or cytotoxic T cells
Each T lymphocytes (T cells) expresses ___
T-cell receptors (TCRs) with a co-receptor (CD) which together recognize a specific intracellular antigen only when presented on MHC
T lymphocytes (T cells) maturation involves ___
Maturation of TCRs and thymic selection
Thymic selection consists of the ___
Positive selection (keeping) and negative selection (removing)
Positive selection consists of
Keeping of T cells that bind self MHC
T lymphocytes (T cells) travel to lymphoid tissue (such as the spleen or lymph nodes) as ___
Naive T cells and are activated by recognizing matching intracellular antigens which are presented on MHC
BCR has ___ binding sites
Two antigen
TCR has ___
1 binding site with a co-receptor
BCR binds ___
Extracellular antigens
TCR binds ___
Intracellular antigens presented on MHC
BCR binds to ___
Epitope directly
TCR requires ___
Co-receptor (CD marker) to bind epitope on MHC
The lymphatic system is a ___
Network providing an alternate route for interstitial fluid (15-20%)
The colorless fluid become lymph when it ___
Flows through lymphatic vessels which begin as microscopic lymphatic capillaries in tissue
Lymphatic capillaries allow ___
Interstitial fluid to flow in, but not out
Carry many antigens through the lymph nodes
Empty back into the blood through the subclavian vein
Primary lymphoid organs include ___
Bone marrow and the thymus
Primary lymphoid organs are sites of ___
Production and maturation of lymphocytes
Secondary lymphoid organs are sites of ___
Throughout the body where lymphocytes and phagocytes gather and contact antigens (ex: lymph nodes, spleen, tonsils, adenoids, MALT (peyer's patch)
Inflammatory responses cause more fluid to ___
Enter tissues which increases antigen-containing fluid entering the lymphatic system
Mucosa-associated lymphoid tissue (MALT) is a ___
Diffuse sampling system scattered along our mucosal linings providing protection against pathogens (ex: Peyer's patches in the small intestine)
Immunoglobulins (Ig) are produced by ___
B cells (soluble Ab or BCR)
What do immunoglobulins (Ig) look like?
Y-shaped soluble proteins with 2 arms (fab) and a stem (Fc)
Immunoglobulins (Ig) have two copies, ___
Heavy chain and a light chain domains joined by an S-S
Immunoglobulins (Ig) have two regions, a ___
Variable region and a constant region
The variable region on immunoglobulins (Ig) is made up of ___
2 specific antigen-binding sites
The constant region on immunoglobulins (Ig) is made up of ___
1 of 5 unique functional classes which are IgG, IgM, IgA, IgD, or IgE
The constant region is the same for all antibodies of a particular class, but ___
Different amongst the different classes
Only IgG (2x) and IgM (1x) can ___
Activate the complement system
IgM is the first antibody ___
Produced in a primary response
IgG can cross the ___
Placenta and is the first antibody produced in a secondary response
IgA is expressed in ___
Milk and mucosal immunity
IgG, IgD, and IgE are all ___
Monomers
IgM is a ___
Pentamer which means that it has 10 antigen-binding sites
IgA is mostly present as a ___
Dimer with a secretory component and a J chain, this means that it has 4 antigen-binding sites
IgG is the ___
Small Ig, and can exit the bloodstream to enter tissues
IgG provides ___
Long-term protection, its half-life in serum is 23 days
IgG is generally the ___
First and most abundant serum Ig during a secondary response
IgM is targets ___
Bloodstream infections because of its large size which prevents crossing from the bloodstream
IgA in its secreted form is important in ___
Mucosal immunity in the GI, genitourinary, and respiratory tracts
IgA protects ___
Breastfed infants against intestinal pathogens
IgA secretory peptide helps ___
Resist enzymatic runs in mucous and helps immobilization
What are the protective outcomes of antibody-antigen binding?
Agglutination, opsonization, neutralization, complement system activation, and antibody-dependent cellular cytotoxicity (ADCC)
Agglutination is the ___
Reduces the number of infectious pathogens to be dealt with by clumping them together and immobilizing them
Opsonization helps ___
Enhance phagocytosis by coating the antigen with antibodies
Neutralization ___
Prevents toxins and viruses from binding to the cell
Complement system activation causes ___
Inflammation and cell lysis
Antibody-dependent cellular cytoxicity (ADCC) is an ___
Infected host cell or pathogenic cell targeted for destruction by immune cells (NK cells, eosinophils, and/or macrophages)
A humoral (antibody-mediated) immune response is activated by ___
An extracellular antigen
A cell-mediated immunity is activated by ___
An intracellular antigen presented on MHC
A humoral (antibody-mediated) immunity defends against ___
Extracellular pathogens by binding to antigens, thereby neutralizing them or making them better targets for phagocytes and complement proteins
A cell-mediated immunity defends against ___
Intracellular pathogens and cancer by binding to and initiating apoptosis in infected cells or cancerous cells
A humoral (antibody-mediated) immunity is carried out by ___
Antibodies against extracellular pathogens, but more specifically antigens
In a humoral (antibody-mediated) immunity, each naive mature B cell carries ___
Highly specific BCRs on their surfaces
In a humoral (antibody-mediated), most B cells require helper T cell ___
Confirmation for activation by a T-dependent antigen
During the maturation stage of a humoral immune response, ___
Stem cells differentiate into mature B cells, each bearing surface Igs against a specific antigen
During the activation or clonal selection stage of a humoral immune response, ___
B cell II encounters its specific antigen and proliferates
During the clonal expansion stage of a humoral immune response, ___
Some B cells proliferate into long-lived memory cells, which at a later date can be stimulated to become antibody-producing plasma cells. Other B cells proliferate into antibody-producing plasma cells
During the humoral response stage of a humoral immune response, ___
Plasma cells secrete antibodies into circulation
During a T-dependent humoral response, BCRs ___
Recognize and attach to antigens
During a T-dependent humoral response, antigens are ___
Internalized (receptor-mediated endocytosis) and degraded into fragments
During a T-dependent humoral response, antigen fragments are ___
Displayed on MHC class II on B cells, attracting a matching helper T cell
During a T-dependent humoral response, helper T cells ___
Secrete cytokines (ILs) which activate B cells (clonal selection)
During a T-dependent humoral response, the activated B cells ___
Begin clonal expansion, producing an army of antibody producing plasma cells and memory cells (clonal expansion)
During the primary response in a humoral immune response, a response usually takes ___
10-14 days for substantial antibody accumulation
During the primary response in a humoral immune response, a person usually will ___
Be sick although the immune system is actively responding
During the primary response in a humoral immune response, B cells undergo ___
Affinity maturation and class switching
Affinity maturation is the process of ___
Natural selection which improves Ig's affinity
During class switching, IgM is ___
The first antibody isotope produced by plasma B cells
During class switching, helper T cells can induce activated ___
B cells to secrete other antibody classes by switching gene activation
During class switching, B cells in the lymph nodes usually ___
Switch to IgG
During class switching, MALT B cells usually ___
Switch to IgA
Memory B cells are formed after ___
Maturation and switching
During the secondary response in a humoral immune response, a response usually occurs ___
Significantly faster and more effective than a primary response. Its a better quantity and a better quality response
During the secondary response in a humoral immune response, memory B cells are responsible for a ___
Greater number for immune cells present.
Receptors already fine-tuned through affinity maturation
When memory B cells are activated during the secondary response in a humoral immune response, they ___
Become plasma B cells which produce antibodies. Often IgG or IgA directly due to class switching from a primary response
During the secondary response in a humoral immune response, IgM is produced by
Newly activated B cells
A second exposure to antigens yield ___
A much faster secondary response due to memory B cells formed during the primary response
During a cell-mediated immune response, helper T cells and cytotoxic T cells have ___
TCR and CD (Cluster of Differentiation) to recognize antigens only presented on MHC of other cells (MHC and antigen)
Cytotoxic T (CD8) cells recognize antigens presented on ___
MHC class I molecules of any uncleared host cell
Helper T (CD4) cells recognize antigens presented on ___
MHC class II molecules on an antigen-presenting cell (APCs = dendritic cells, macrophages, B cells)
What are the main CD subsets of T cells?
CD8 (cytotoxic T cells) and CD4 (helper T cells)
What are the main classes of MHC?
Class I and class II
All nucleated cells present ___
Endogenous antigens on MHC class I molecules
B cells and macrophages present ___
Exogenous antigens on MHC class II molecules
Step 1 in the cell-mediated immunity mechanism is referred to as clonal selection, this step consists of ___
Dendritic cells migrating through the lymph and present epitope on MHC to mature naive T cells
Step 2 in the cell-mediated immunity mechanism is referred to as clonal expansion, this step consists of ___
Activated T cells proliferate and differentiate into effector T cells and memory T cells
Activated cytotoxic T (CD8) cells, by MHC 1-bound antigen, differentiate into effector cytotoxic T cells (CTLs) and memory cytotoxic T cells
Activated helper T (CD4) cells, by MHC II-bound antigen, differentiate into effector helper T cells and memory helper T cells
Activated cytotoxic T cells destroy ___
Infected cells in the body
Activated helper T cells secrete cytokines that activate ___
Cytotoxic T cells and NK cells, activate macrophages to enhance phagocytosis, and activate B cells
What are the effector functions of cytotoxic T (CD8) cells?
Recognize antigens on MHC class I of infected host cells
CD8 cells induce apoptosis by releasing digestive enzymes (perforins and granzymes), and also releases cytokines that alert neighboring cells
Memory cytotoxic T cells ensure ___
A faster secondary response
What are the effector functions of helper T (CD4) cells?
Recognize antigens presented on MHC class II of APCs
Secrete cytokines
Cytokines secreted by helper T (CD4) cells ___
Activate B cells and induce B cells clonal expansion
Activate macrophages to increase power and fuse to form giant cells: increased size, metabolism, and the number of lysosomes
Direct and support cytotoxic T (CD8) cells proliferation and differentiation
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