The alloantibody response in the allogeneically pregnant rat. I. The primary and secondary responses and detection of Ir gene control.

We compared the primary pregnancy-induced alloantibody responses with secondary pregnancy-induced responses and with conventional immunologic responses and found there are profound differences. Conventional and secondary responses produce strong lytic sera and readily detectable immunologic memory. The primary pregnancy-induced responses lack memory and produce alloantisera or widely variable titer. Such sera were rarely directly lytic. Pregnancy-induced primary responses detect MHC Ir gene control, even when the allogeneic difference is a complete HMC haplotype. The kinetics of the primary and secondary pregnancy-induced alloantibody responses against DA were different. We conclude that the primary pregnancy-induced alloantibody response is very different immunologically from conventional and secondary pregnancy-induced alloimmunizations.