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")
Colostrum natural colostrum nearly always had higher antibody titers than did the hyperimmune version clinical trials have shown that if the immunization is by surface antigens of the bacteria,the Bovine Colostrum Powder can be used to make tablets capable of binding to the bacteria so that they are excreted in stools. This prevents the successful colonization of the gut, which would otherwise lead to bacteria releasing enterotoxigenic materials. These small immune signaling peptides (PRPs) were independently discovered in colostrum and other sources, such as blood plasma, in the United States, Czechoslovakia and Poland. Hence they appear under various names in the