Production of an HLA-DRw13 antibody in a DRw14 positive multiparous woman.

A lymphocytotoxic HLA-DR alloantiserum (Ma159) which reacts with DR7, DR5 and DRw13 positive lymphocytes is described. It was non-cytotoxic against 27 DRw14 positive subjects and was not absorbed by DRw14 positive cells. The antiserum was produced by pregnancy alone in a DR4, DRw14 positive woman whose husband possesses DR7 and DRw13. Absorption and titration studies suggested that the antiserum contains separate antibodies directed towards DR7, DRw13 and a determinant shared by DR5 and DRw13. The implications of finding a specific anti-DRw13 antiserum and its production in a donor positive for the alternative subdivision of DRw6 are discussed.