Lack of antibody specificity by mouse trophectoderm during immunosurgery

Immunosurgery of blastocyst-stage embryos is an effective procedure for isolating the inner cell mass. The ability of rabbit sera antibodies produced to interspecific types of cells to bind to mouse trophectoderm antigens and mediate complement-reactive lysis was investigated. Fifty hatched and 25 expanded blastocysts per treatment were exposed to 1 of 7 heat-inactivated polyclonal antibodies (1: 10 DMEM dilution) produced in rabbits to mouse brain cells (MBr), mouse lymphocytes (MLy), rat lymphocytes (RLy), hamster lymphocytes (HLy), cattle splenocytes (CSp), sheep splenocytes (SSp), and pig splenocytes (PSp). After subsequent incubation in a guinea pig complement solution (1: 16 dilution) the embryos were assessed for trophectoderm lysis, and the inner cell masses were pipetted free of cellular debris. Fewer (P<0.01) hatched blastocysts were lysed completely when treated with RLy (60%), CSp (50%) and PSp (14%) antibodies compared the other treatment groups (100%). A similar response was observed with expanded blastocysts, with the exception that even fewer (P<0.01; RLy, 24%; CSp, 40%; PSp, 0%) were lysed completely. Forty percent of the PSp expanded blastocysts experienced no lysis, which was different (P<0.01) than in all the other treatments. Secondary experiments were performed to explain the cause of partial lytic response. Overall, the results indicate that interspecific antibodies can bind to murine trophectoderm surface antigens and mediate immunosurgical inner cell mass isolation, although the trophectoderm lytic response varied with antibody source.