Immunocytochemical typing of ABO blood groups in vaginal swabs partly contaminated with semen

ABH typing by immunocytochemical method has been carried out on 163 selected vaginal swabs. 127 cases (78%) were determined correctly, 11 cases (7%) incorrectly and 25 cases (15%) could not be classified. Often, not all of the vaginal cells showed the expected positive staining, which was not counted as a false result. The incorrect results were not dependent on the secretor status, but 37% of the non-secretor cases could not be classified immunocytochemically, as compared with 12% of the secretors. In a second series, 61 vaginal swabs, dried on microscope slides, have been covered with semen from an A1 B secretor. Absorption of heterologous antigens by the vaginal epithelia could be demonstrated only after extremely long incubation with semen and extremely long incubation with the anti-A or anti-B antibodies. From the 163 "native" swabs, 17 gave a positive reaction with the acid phosphatase test, but only one false ABH result. A possible influence of bacteria upon the results is discussed. We believe that in practice, no faults in immunocytochemical ABH typing have to be expected, due to absorption of heterologous antigens.