GPLA antigens are not expressed on guinea-pig epididymal spermatozoa.

The expression of guinea-pig major histocompatibility antigens (class I and II) has been investigated on guinea-pig epididymal spermatozoa. Specific alloantisera (anti-B1, anti-B3, anti-Ia2,4 and anti-Ia1,3,7) were obtained by cross-immunization of strains 2, 13 and BIO-AD animals with relevant spleen cell membranes. These sera were tested on spermatozoa from the same three strains by a protein A rosetting assay and by an indirect immunofluorescence test. The results obtained showed non-strain specific reactions of all the alloantisera tested on epididymal spermatozoa of the three strains. These non-strain specific reactions were absorbed by spermatozoa of any strain but they were not absorbed by the splenic cells of the same animals. On the other hand, the alloantisera specific reactivity on peripheral blood cells was not diminished after incubation of the sera with spermatozoa. Furthermore anti-B1 and anti-B3 antibodies eluted from guinea-pig platelets did not react with any spermatozoa but reacted with the relevant peripheral blood cells. These results indicate that the studied guinea-pig sera contained two types of antibodies: anti-MHC antibodies able to react with relevant blood cells but not with spermatozoa and sperm specific antibodies (also observed in untreated and DNP-BGG immunized guinea-pig sera) reacting with all spermatozoa but not with blood cells. They are not compatible with the expression of MHC antigens at the surface of guinea-pig epididymal spermatozoa.