Talk:2009 Lab 4
IgA - Found in mucosal areas, such as the gut, respiratory tract and urogenital tract, and prevents colonization by pathogens. Also found in saliva, tears, and breast milk.
IgD - Functions mainly as an antigen receptor on B cells that have not been exposed to antigens.
IgE - Binds to allergens and triggers histamine release from mast cells and basophils, and is involved in allergy.
IgG - In its four forms, provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to fetus.
IgM - Expressed on the surface of B cells and in a secreted form with very high avidity. Eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there is sufficient IgG.
(modified from Wiki Table)