Basic Sciences

Question 1

Describe cells involved, site/target of action, and timing of response for innate immune response

Answer 1

Cells involved: Leukocytes
Site/Target of action: Local, confined, non-specific
Timing: Early (hours); “first responder”

Question 2

Describe cells involved, site/target of action, and timing of response for adaptive immune response

Answer 2

Cells involved: Lymphocytes
Site/Target of action: Global, spreading, specific epitope
Timing: Late (days); “last resort”

Question 3

Breifly describe the two stem cell lines arising from the pluripotent hematopoietic stem cell

Answer 3

Myeloid stem cells: Form all leukocytes except lymphocytes, erythrocytes, and megakaryocytes.
Lymphoid stem cells: Form lymphocytes (B, T, NK)

Question 4

Name site of maturation for the three forms of lymphocytes

Answer 4

B cells: Mature in bone marrow
T cells: Begin maturation in bone marrow and finish maturing in thymus
NK cells: Mature in bone marrow, thymus and secondary lymphatic structures (spleen, tonsils, lymph nodes)

Question 5

Which cells have class I MHC proteins

Answer 5

All nucleated cells (including dendritic cells)

Question 6

Which cells have class II MHC proteins

Answer 6

APCs (dendritic cells, macrophages, B cells)

Question 7

Which lymphocyte recognizes class I MHC proteins; source of antigen; displaying antigen means…

Answer 7

Lymphocyte: CD8 cells (cytotoxic T cells)
Source: Endogenous (intracellular pathogens/proteins made by CA cells)
Message: “I belong to self but have been invaded or am cancerous. Kill me!”

Question 8

Which lymphocyte recognizes class II MHC proteins; source of antigen; displaying antigen means…

Answer 8

Lymphocyte: CD4 cells (helper T cells)
Source: Exogenous (phagocytized extracellular pathogens)
Message: “I belong to self but have captured an invader. This is what it looks like, help me mount a defense.”

Question 9

Name three cells that function as antigen presenting cells (APCs)

Answer 9

Macrophages
B cells
Dendritic cells

Question 10

How do APCs process a microbe? What cell do they target?

Answer 10

APCs take in antigen, chop it up, stick a piece onto a class II MHC protein, and presents this complex on its surface.
The APC presents this complex to helper T cells for further activation of immune response.

Question 11

Immunoglobulin G: structure (complexity), when produced (early/late), what immune cells have receptors for constant/Fc end?

Answer 11

Structure: Monomer
Produced: Primary response - late; Secondary response - early (from memory cells)
Immune cells: Macrophages/neutorphils/ dendritic cells (phagocytosis), NK cells (induction of antibody-dependent cell-mediated cytotoxicity); transfer to fetus through placenta for passive immunity.

Question 12

Immunoglobulin A: structure (complexity), when produced (early/late), location?

Answer 12

Structure: Monomer; dimer (secretory form)
Produced: Transferred from blood and into surface of mucosa.
Location: Secretory organs (mucosa of GI, saliva, respiratory, urogenital, sweat, tears, breast milk).

Question 13

Immunoglobulin M: structure (complexity), when produced (early/late), location?

Answer 13

Structure: Pentamer (10 binding sites).
Produced: First responder because of amount of binding sites.
Location: Free floating.

Question 14

Immunoglobulin E: structure (complexity), when produced (early/late), what immune cells have receptors for constant/Fc end?

Answer 14

Structure: Monomer
Produced: parasitic worms; allergens
Immune cells: Mast cells (early) and eosinophils (late) (degranulation)

Question 15

Immunoglobulin D: structure (complexity), when produced (early/late), location?

Answer 15

Structure: Monomer
Produced: Unknown function
Location: B cell receptor

Question 16

What are the two processes by which lymphocytes that recognize self-antigens are eliminated during development?

Answer 16

Clonal deletion and clonal activation

Question 17

Define clonal deletion

Answer 17

Developing T cells in thymus during fetal and early postnatal development; those binding to self proteins are destroyed by apoptosis.

Question 18

Define clonal inactivation

Answer 18

Self-reacting T cells in periphery become nonresponsive.

Question 19

Describe the better name and process of Type I Hypersensivity and what antibodies are involved, chemical mediators released.

Answer 19

Better name: Immediate or anaphylactic
Process: Requires two exposures. First exposure - B cells differentiate into IgE producing plasma cells. IgE produced, binds mast cells. Second exposure: Same antigen cross links IgE bound to mast cells. Mast cells degranulate releasing histamine, lipid mediators, cytokines.
Antibodies: IgE
Chemical mediators: Histamine, eicosanoids, chemokines.
This is common allergies

Question 20

Describe the better name and process of Type II Hypersensivity and what antibodies are involved, chemical mediators released.

Answer 20

Better name: Cytotoxic hypersensitivity
Process: Antibody binds directly to antigen in tissue or on cell. Mediate Fc receptor and complement to activate leukocytes (phagocytosis, inflammation, tissue injury)
Antibodies: IgG/IgM (rarely)
Chemical mediators: Complement and antibody-directed process

Question 21

Describe the better name and process of Type III Hypersensivity and what antibodies are involved, chemical mediators released.

Answer 21

Better name: Immune complex-mediated hypersensitivity
Process: Antigen-antibody complexes deposited in small vessels (skin, kidney, joints). Common causes: systemic lupus erythematosus, serum sickness.
Antibodies: IgG/IgM (rarely)
Chemical mediators: Precipitate activates complement

Question 22

Describe the better name and process of Type IV Hypersensivity and what antibodies are involved, chemical mediators released.

Answer 22

Better name: Delayed hypersensitivity
Process: Primed CD4 cells bind to reexposed antigen, release cytokines, stimulating neutrophils to cause inflammation and tissue injury. Primed CD8 cells bine to reexposed antigen, cause cellular death and tissue injury. Caused by: TB testing, Ni allergy, contact dermatitis (poison oak).
Antibodies: None (T cell mediated)
Chemical mediators: Cytokines