immunoglobulin alpha 1 heavy chain constant region
Ig alpha is the major immunoglobulin class in body secretions. It may serve both to defend against local infection and to prevent access of foreign antigens to the general immunologic system. In normal adult serum, the approximate percentage composition of IgA with respect to is subclasses is IgA1:90% and IgA2:10%. In secretory IgA, the subclass proportions may approach 50:50. The clinical significance of the subclasses has yet to be determined.