Immunological block to mammalian fertilization: survival and organ distribution of immunoglobulin which inhibits fertilization in vivo.

Fertilization of golden hamster eggs was blocked both in vitro and in vivo by antibodies produced in rabbits against specific hamster ovarian antigens (HOA). Antibodies against HOA bound to surfaces of the hamster egg zona pellucida and prevented spermatozoa from attaching to the zona and entering eggs in vitro. Fertilization in animals could be blocked for four estrous cycles by a single intraperitoneal injection of anti-HOA immunoglobulin, but not by control immunoglobulin. The in vivo fate of anti-HOA immunoglobulin was analyzed by simultaneous injection of 125I-anti-HOA IgG and control 131I-IgG. Both anti-HOA IgG and control IgG appeared in a variety of organs (lung, kidney, spleen, liver, and uterus) shortly after injection, but disappeared rapidly with no detectable differences in organ half lives. However, in the ovary anti-HOA IgG (but not control IgG) persisted at high levels during the period of infertility. Quantitative precipitin analysis of organ homogenates indicated that a high percentage of anti-HOA IgG in the ovary (but not in the other organs tested) was immunologically indistinguishable from IgG indicating lack of radiolabel metabolism and reincorporation. The results are discussed in terms of the development of a specific immunological block to fertility.