Immunoglobulin A only weakly. IgA exists in two isotypes, IgA1 and IgA2. They are both heavily glycosylated proteins. While IgA1 predominates in serum (~80%), IgA2 percentages are higher in secretions than in serum (~35% in secretions); the ratio of IgA1 and IgA2 secreting cells varies in the different lymphoid tissues of the human body: Both IgA1 and IgA2 have been found in external secretions like colostrum, maternal milk, tears and saliva, where IgA2 is more prominent than in the blood. Polysaccharide antigens tend to induce more IgA2 than protein antigens. Both IgA1 and IgA2 can be in membrane-bound form. ("see B-cell receptor")
Sesquilinear form form, it follows that, for all , It also follows that is a fixed point of the map . The fixed points of this map from a subgroup of the additive group of . A -Hermitian form is reflexive, and every reflexive -sesquilinear form is -Hermitian for some . In the special case that is the identity map (i.e., ), is commutative, is a bilinear form and . Then for the bilinear form is called "symmetric", and for is called "skew-symmetric". Let be the three dimensional vector space over the finite field , where is a prime power. With respect