RED BLOOD CELL ALLOANTIGENIC SYSTEMS IN THE RAT

A new alloantigenic system on red blood cells, Ag‐S, is described: the Ag‐S1 allele is present in the SHR strain, and all other strains tested possess the allelic Ag‐S2 specificity. The Ag‐C system, which was previously described using xenogeneic antisera, was shown to be an alloantigenic system. The appropriate strain combinations are needed to elicit detectable antibodies, and the variability of the antigenic strength of this system can lead to problems in histocompatibility (Ag‐B, H‐1) typing. The Ag‐D system was explored using both allogeneic and xenogeneic antisera. All three red cell systems are not linked to each other and are not linked to Ag‐B (H‐1). They are not isoantigenic systems, at least in the classical sense, since a variety of normal rat sera did not contain agglutinating antibodies to these antigens. Antibodies raised in various strain combinations are haemagglutinating but are not cytotoxic. The three antigenic systems serve as useful markers in delineating strains and substrains, and a variety of inbred strains of animals were typed using these reagents.