Tissue Typing Antisera from Immunization by Pregnancy

Anti‐HL‐A antibodies developing during pregnancy were investigated and identified in 1400 pregnancy sera. Of these 169 (12 %) were observed to be strongly reactive with at least 1 out of 20 lymphocytes. A panel of 33 lymphocyte donors phenotyped for 22 HL‐A antigens was used for the determination of antibody specificity in the reactive sera. During this investigation 11 sera showing a perfect or almost perfect correlation with one known HL‐A specificity were identified. Fifteen other useful sera showed correlation with more than one HL‐A specificity. Eight additional sera reacted with patterns that did not fit a defined group but suggested the possibility of reactions with as yet unidentified HL‐A antigens. The results of this study demonstrate that the development of tissue typing reagents from pregnancy sera in a clinical tissue typing laboratory can be highly productive.