Major histocompatibility complex-linked spleen-dependent transfusion "collapse curves" in inbred rats

In most donor-host combinations among seven inbred rat strains, transfused allogeneic red blood cells were cleared from the circulation of unsensitized hosts at a rate no different from that of syngeneic red blood cells. In four strain combinations, however, allogeneic red blood cells were cleared very rapidly, and in six combination, clearance was effected at a rate intermediate between the rapid clearance rate and the syngeneic rate. In strain combinations exhibiting rapid clearance, females cleared allogeneic red blood cells significantly more rapidly than did males. Rapid clearance was linked to the major histocompatibility complex (MHC) of the donor strain but not to the MHC of the host strain. All donor-host combinations showing rapid clearance possessed identical RT2, RT3, and AgS red blood cell alloantigens. Red blood cells removed rapidly from the circulation by allogeneic hosts were sequestered in the spleen rather than lysed in the circulation. The phenomenon was mediated by splenic reticuloendothelial cells and could be completely circumvented by prior splenectomy. Rapid clearance was apparently not antibody mediated. The phenomenon of rapid clearance of allogeneic red blood cells in rats appears to be analogous to the "collapse curves" of human blood transfusion.