Immunogenic and antigenic epitopes of immunoglobulins. X: Monoclonal antibodies specific for human IgA, the IgA1 and IgA2 subclasses and an nA2m(2) iso-allotypic epitope.

Monoclonal antibodies (McAb) specific for human IgA, the IgA1 and IgA2 subclasses and the iso-allotypic epitope nA2m(2) have been produced. Three distinct McAb recognize an IgA1-specific epitope expressed in the C alpha 2 domain or the hinge region whilst a further McAb is directed possibly to an IgA1 hinge region epitope. The McAb having nA2m(2) specificity recognizes an iso-allotypic epitope expressed within the Fab region. IgA1 and IgA2 epitopes were detected in gorilla but not rhesus or baboon sera suggesting that the IgA subclasses represent a recent gene duplication even. However, these epitopes were also detected in some non-primate sera.