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What is immunology?

Study of the mechanisms of the immune system

What are the two major types of immunity?

Natural (innate) and Acquired (adaptive)

Which immunity is present at birth and has no memory?

Natural / Innate immunity

Which immunity develops after antigen exposure and has memory?

Acquired / Adaptive immunity

Which immunity has antigen recognition capability?

Acquired / Adaptive immunity

How many lines of defense does the immune system have?

Three

What immunity composes the first and second lines of defense?

Natural / Innate immunity

What immunity composes the third line of defense?

Acquired / Adaptive immunity

What is the primary role of the first line of defense?

Prevent entry of pathogens

What are the physical barriers of the first line?

Intact skin and skin appendages

What skin appendages trap microorganisms?

Nasal hair, eyelashes, cilia

What biochemical enzyme in secretions destroys bacterial cell walls?

Lysozyme

Which secretions contain lysozyme?

Saliva, sweat, tears

What is the normal pH of the stomach?

pH 2

What is the normal vaginal pH?

pH 5.5

Which neurologic responses expel irritants?

Sneezing and coughing

Which parasites can penetrate intact skin?

Necator americanus, Ancylostoma duodenale, Schistosoma spp.

What are the two divisions of the second line of defense?

Cellular and humoral

Which cells perform phagocytosis?

Neutrophils, eosinophils, basophils, monocytes/macrophages

What is the role of phagocytes?

Eat and digest pathogens without memory

What does LGL stand for?

Large Granular Lymphocyte

What are the three forms of LGLs?

NK cells, K cells, LAK cells

What activates LAK cells?

Interleukin-2 (IL-2)

What is phagocytosis?

Ingestion and digestion of microorganisms

What are the steps of phagocytosis in order?

Margination → Migration → Chemotaxis → Engulfment → Digestion → Excretion

What is the neutrophil respiratory burst?

Release of peroxides to kill bacteria

Why is respiratory burst powerful?

It destroys bacterial cell walls

What eosinophil protein kills larvae and parasites?

Major basic protein (MBP)

What is the main function of basophils?

Release histamine

What is a dangerous side effect of histamine?

Bronchoconstriction

What receptors do NK cells use?

Killer activation receptor and killer inhibition receptor

What do stressed or infected cells express for NK recognition?

Stress-associated molecules

What substances do NK cells release to kill targets?

Perforin and granzyme

What is the “kiss of death” phenomenon?

NK cell attaches and releases lethal granules

What is ADCC?

Antibody-dependent cellular cytotoxicity

Which antibody mediates ADCC?

IgG

Which cells can perform ADCC?

NK cells, macrophages, neutrophils, monocytes

Which cells have IgE receptors for ADCC?

Eosinophils and basophils

What does MHC stand for?

Major Histocompatibility Complex

What are HLAs?

Human Leukocyte Antigens

Where is MHC Class I found?

All nucleated cells

Which HLAs are in MHC Class I?

HLA-A, HLA-B, HLA-C

Where is MHC Class II found?

Antigen-presenting cells

Which HLA is associated with MHC Class II?

HLA-D

Why are RBCs not targets for NK cells?

They lack MHC molecules

Which cells are APCs?

Macrophages, B cells, dendritic cells

What molecule is required to be an APC?

MHC Class II

What is the job of APCs?

Present antigens to lymphocytes

Which lymphocyte first interacts with APCs?

T-helper cell (CD4+)

What CD marker identifies T-helper cells?

CD4+

Why are T-helper cells pivotal?

They release IL-2

What does IL-2 do?

Activates the entire immune system

Which virus targets CD4+ cells?

HIV

Which interleukins produce Th1 cells?

IL-2 and IL-12

Which interleukins produce Th2 cells?

IL-2, IL-4, IL-10

What immune response is Th1 associated with?

Cell-mediated immunity

What immune response is Th2 associated with?

Humoral immunity

What CD marker identifies T-cytotoxic cells?

CD8+

Which cells activate T-cytotoxic cells?

Th1 cells

How do T-cytotoxic cells kill infected cells?

Perforin and granzyme

Do T-cytotoxic cells have memory?

Yes

Which cells drive humoral immunity?

B cells

What do B cells differentiate into?

Plasma cells and B-memory cells

What do plasma cells produce?

Antibodies

Where do B-memory cells reside?

Secondary lymphoid organs

What characterizes the primary immune response?

Long lag period

Which antibodies appear first in primary response?

IgM then IgG

What predominates in secondary immune response?

IgG

Why are boosters needed in vaccination?

To increase memory cells

Which immunoglobulin is pentameric?

IgM

Which immunoglobulin crosses the placenta?

IgG

Which immunoglobulin is secretory?

IgA

Which immunoglobulin is associated with allergy?

IgE

Which immunoglobulin is a B-cell receptor?

IgD

How many heavy chains are in an antibody?

Two

How many light chains are in an antibody?

Two

What bonds hold antibody chains together?

Disulfide bonds

What fragment binds antigen?

Fab fragment

What fragment is constant?

Fc fragment

Which region determines idiotype?

Variable region

What is an epitope?

Antigenic determinant site

Which CH domain binds complement?

CH2

Which CH domain allows placental transfer?

CH3

Which immunoglobulin can cross the placenta?

IgG

What is opsonization?

Antibody-enhanced phagocytosis

What is neutralization?

Blocking toxins or pathogens

What causes antibody-mediated cytotoxicity?

Complement activation

What is the pivotal complement protein?

C3

What is the endpoint of complement activation?

Membrane Attack Complex (MAC)

Which pathway requires antibody?

Classical pathway

Which antibody best activates classical pathway?

IgM

Which pathways do not require antibody?

Lectin and alternative

What triggers C1 activation?

Antigen-antibody reaction

What stabilizes the C1 complex?

Calcium

What is the C3 convertase of the classical pathway?

C4b2b

What triggers the lectin pathway?

Mannose on bacteria

What protein binds mannose?

Mannose-binding protein (MBP)

What replaces C1 in lectin pathway?

MBP

What stabilizes C3bBb?

Properdin and magnesium

What is the C3 convertase of the alternative pathway?

C3bBb