Week 6 S - Antibodies

Vocabulary flashcards about Cells & Immunity.

IgG

Three hypervariable regions within each Vн and VL domain.

Generation of Antibody Diversity (GOD)

Antibody diversity is generated from a few hundred Ig genes through the use of gene segments.

Isotype of Antibody

Determined by the HEAVY chain present; includes IgA, IgD, IgE, IgG, and IgM.

Light Chains (L chains)

Can be either kappa (k) or lambda (l).

IgM

Major Ig class of primary immune response; confined to the vascular system.

IgG

Major Ig class of secondary immune response; can cross capillary walls to reach extracellular fluid.

IgA

Major Ig class found in sero-mucus secretions of the body (saliva, gut, airways, genito-urinary tract etc); also secreted in breast milk.

IgE

Found bound to mast cells and basophils; involved in triggering mast cell degranulation.

IgD

Mainly found on the surface of B cells; serves as an antigen receptor at certain stages of B cell differentiation.

Primary Role of Antibodies

Specific binding to antigen.

Secondary Role of Antibodies

B cell antigen receptor.

Agglutination

Restricts spread of microbes throughout the body and facilitates phagocytosis.

Opsonization

Tagging an antigen target with an antibody to enhances efficiency of phagocytosis.

Neutralization of Microbial Toxins

Prevents toxicity.

Secretory IgA

Dimeric form blocks microbe adherence and neutralizes toxins.

Ab-dependent cell-mediated cytotoxicity (ADCC)

Non-specific cytotoxic cells bind Ab-coated targets via their Fc receptors (FcγRIII).

IgE

Triggers degranulation of antigen-sensitized mast cells.

IgG

Passive transfer in the placenta via neonatal Fc receptor (FcRn).

IgA

Passive transfer in the mammary gland via poly-Ig receptor (pIgR).