MAM: a "new" high-incidence antigen found on multiple cell lines

Three women have been identified with an antibody to a "new" high-incidence antigen found on multiple cell lines.

The proposita, M.A.M., presented during her third pregnancy with an antibody reacting with all RBCs tested except her own. She delivered a thrombocytopenic infant with a 3+ DAT, but without symptoms of HDN. The second example, A.N., presented during her third pregnancy with an antibody reacting with all RBCs tested except her own and those of M.A.M. She delivered a slightly thrombocytopenic but severely anemic infant. The third example, F.K., a sister of A.N., has an antibody reacting with all RBCs tested except her own and those of M.A.M. and A.N.

This "new" high-incidence antigen has been named MAM and assigned high-incidence antigen number 901016 by the International Society of Blood Transfusion. The corresponding antibody, anti-MAM, has been shown to cause HDN and has the potential to shorten RBC survival after the transfusion of incompatible RBC units, as determined by monocyte monolayer assay. Immunoblotting and flow cytometry show that this new antibody reacts with various WBC lines in addition to RBCs. This antibody also appears to react with platelets in some assays.