Immunology Flashcards
external defenses
skin, mucous membrane, and enzyme secetions
internal defenses
phagocytes, antimicrobial proteins, inflammation, and natural killer cells
neutrophil
phagocyte; 60-70% of leukocytes; life span few days; home to infected tissue
macrophage
develop from monocytes; some reside in specific lymphatic tissue
eosinophil
low phagocyte activity; defense against multicellular parasites with enzymes
dendritic cell
phagocytic, but primary role is stimulating acquired immunity
interferon alpha + beta
provide innate defense against viral infections
complement system
30 serum proteins that are antimicrobial proteins
mast cells
releases histamine, which triggers dilation and increased permeability of nearby capillaries
chemokine
small proteins of cytokine family that attract phagocytic cells
natural killer cells
innate defense; attack virus infected cells and cancer cells causing apoptosis
hemocytes
insect white blood cells found in hemolymph
cytokines
phagocytes secrete these proteins that help activate lymphocytes
lymphocytes
B or T cells with about 100,000 identical antigen receptors on the surface
Immunoglobulins
structurally similar to B cell receptors, but lack a transmembrane domain
B cell receptors
noncovalent bonds with intact antigens
T cell receptors
one a and b chain; recognizes small fragments of antigens that are bound to MHC molecules
class I mhc
found on almost all nucleated cells; antigen display is recognized by cytotoxic T cells
class II mhc
made on antigen presenting cells dendritic cells, macrophages, and b cells; display is recognized by helper T cells
thymus
lymphocytes that migrate from bone marrow to here develop into T cells
lymphocyte activation
binding of antigen activates lymphocyte and stimulates division into clones
humoral immune response
plasma and memory b cells; secretion of antibodies
cell mediated immune response
activation and clonal selection of cytotoxic t cells
CD4
present on helper T cells; binds to the class II MHC molecule
dendritic cell-T cell
effective in presenting antigens to naive helper T cells
macrophage - T cell
initiate a secondary immune response by presenting antigens to memory helper T cells
B cell - T cell
primarily present antigens to helper T cells during humoral response
CD8
present on cytotoxic T cells; binds to the class I MHC molecule
helper T cell activation
binds to antigen-MHC II complex with TCR and secretes cytokines for B cells and cytotoxic T cells; produces helper T clones
cytotoxic T cell activation
with the help of MHC I and cytokines perforin and granzymes are released causing apoptosis
plasma B cells
after activation these effector cells secrete antibodies to the antigens that this B cell is specific for
B cell internalization
dendritic cell internalizes peptide fragments from variety of antigens; presents only antigen to which it specifically binds
T dependent antigen
induce antibody production only with assistance from helper T cells
T independent antigens
weaker response with bacteria capsules and flagella; does not generate memory B cells
memory B cells
activated effector B cells with antibodies on the membrane
polyclonal antibody
products of many different clones of B cells, each specific for a different epitope
monoclonal antibody
identical and specific for the same epitope on an antigen
viral neutralization
antibodies bind to surface of virus and blocks host binding as well as enhancing phagocytosis
opsonization
binds to pathogenic bacterium and enhances macrophage phagocytosis
antigen precipitation
antibodies cross link soluble antigen molecules and aggregates
agglutination
clumps bacteria or virus for phagocytosis; commonly performed by IgM
antibody-complement proteins
complement proteins bind to antigen-antibody complex and causes cell lysis
IgM
pentamer; first Ig class produced after initial antigen exposure; agglutination
IgG
confers passive immunity on fetus; most abundant Ig in blood
IgA
dimer; present in secretions; confers passive immunity in milk; mucous membrane defense
IgE
triggers release of histamine from mast cells and basophils that cause allergic reaction
IgD
present on surface of naive B cells; antigen receptors in antigen stimulated proliferation of B cells
