Immunology and Immune Disorders Overview of Adaptive Immunity

adaptive immunity discovery: smallpox

immunoglobulin and t-cell receptors are highly variable recognition molecules of adaptive immunity

B cells and antibodies

• Antibodies also known as immunoglobulins
• structure of IgG shown (DIAGRAM)
• other classes of Ig: IgA, IgD,IgE and IgM
• all types of antibodies are produced by B cells (b Lymphocytes) which mature into plasma cells
• antibody binding sites vary in shape and properties

b cells and clonal expansion(stimulation of the production of lymphocytes)

total of ~3 billion blood cells, 100 million different b cells, ~30 b cells that can produce a particular antibody which binds a particular antigen, more produced by clonal expansion

b cells and clonal expansion

b cell receptors (BCRs) - 1st batch of antibodies[1000's of b cell receptors per b cell each with same specificity. SEE IMAGE

when BCR binds cognate antigen, b cell is activated, starts proliferating = 20,000 identical b cells. ~30 cells to ~20,000 cells in a week

activated b cell= plasma/ memory cell

plasma cells pumps out ~2000 antibodies a second

PLASMA CELLS DIE MEMORY CELLS REMAIN

Antibodies: 

• identify and tag for destruction
• opsonise molecule enhancing phagacytosis
• neutralize antibodies block the site on pathogen that they use to enter the target cell

IgM - fixing complement, good opsonizer, 1st anitbody

IgG- fixes complement, opsonizer, neutralize virus, helps NK cells by antibody dependant cellular cytotoxicity (ADCC)

IgA - protects mucosal surface, breast milk, resistant to proteases

IgE - defends against parasites

IgD - mainly as BCR (together with IgM) where controls activation and suppression. 

T-cells lymphocytes = 1 trillion

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