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")
Genus of a quadratic form Genus of a quadratic form In mathematics, the genus is a classification of quadratic forms and lattices over the ring of integers. An integral quadratic form is a quadratic form on Z, or equivalently a free Z-module of finite rank. Two such forms are in the same "genus" if they are equivalent over the local rings Z for each prime "p" and also equivalent over R. Equivalent forms are in the same genus, but the converse does not hold. For example, "x" + 82"y" and 2"x" + 41"y" are in the same genus but not equivalent over Z. Forms in