Antibodies to sperm surface antigens and the c-myc proto-oncogene product inhibit early embryonic development in mice

The effects of antibodies against sperm antigens and the c-myc proto-oncogene product on early embryonic development were investigated in mice. Affinity-purified Fab ’ antibodies against lithium diiodosalicylate (US)-solubilized murine sperm extract and fertilization antigen (FA-1) reduced (p < 0.01 top < 0.001) blastulation rates of in vitro cultured 2-cell murine embryos primarily because of an arrest of development at the morula stage. Similarly, the c-myc monoclonal antibody (mAb) affected early embryonic development in a dose-dependent manner. These effects were specific, since immunoabsorption, with its re-spective peptide, completely blocked the inhibitory effect of the c-myc mAb. Anti-US sperm Fab ’ identified four protein bands (approx. 36, 29, 24.6, and 17.6 kDa) on Western blots of extracts from unfertilized and fertilized ova, one band (approx. 68 kDa) each on 4-8-cell embryo and morula extracts, and one band (approx. 53 Wa) on blastocyst extracts. Anti-FA-1 Fab ’ did not react with unfertilized or fertilized ova, but specifically identified two protein bands (approx. 53 and 25.7 kDa) on blots of 2-cell-embryo extract, one band (approx. 25.7 kDa) on morula extract, and one band (approx. 53 kDa) on blastocyst extract. The c-myc mAb did not react with any band corresponding to the c-myc protein on blots of extracts from unfertilized or fertilized ova, 2-cell embryos, 4-8-cell embryos, morulae, or blastocysts. These results suggest that some of the cross-reacting sperm antigens that are expressed during early cleavages, and the product of the c-myc proto-oncogene may have a role in normal early embryonic development