Characterization of the RT2 antigens of the rat erythrocyte membrane

Production of monoclonal antibodies against RT2 antigens of the rat and the definition of a new locus, RT9, linked to RT2

Efforts were made to generate hybridomas producing monoclonal antibodies against the RT2a, RT2b and RT3a antigens of the rat. While a number of hybridomas from each of five different fusions was found to produce antibodies against the RT2b antigen, no hybridoma producing antibody to the RT2a antigen could be detected among those generated in six different fusions. No stable hybridoma secreting antibody specific for the RT3a antigen could be established in three different fusions, although one positive culture was detected. In the course of this work, a monoclonal antibody against a new antigenic specificity was detected in one of the two strain combinations in which the anti-RT2b antibodies were raised. The locus controlling this antigen, which was designated RT9, maps 4.9 (2.2-12.6) cM from RT2.

Immunochemical evidence for multiple class I antigens coded by the MHC of the rat (RT1) and their differential expression on red blood cells and lymphocytes

Five monoclonal antibodies reacting with class I MHC antigens were produced by fusing lymphocytes from WF (RT1u) rats immunized against DA (RT1a) rats with P3-X63-Ag8.653 myeloma cells. Sequential immunoprecipitation studies with the mAb and the WF anti-DA alloantiserum demonstrated the presence of four different class I molecules: all four molecules were reactive with the alloantiserum; three of them contained the determinant for mAb 155; two of the latter three molecules shared the determinants for mAb 3, 56 and 60, and one of these two molecules also contained the determinant for mAb 118. The four molecules could be isolated from the antigen preparation by sequential immunodepletion first with 118, next with 3, then with 115 and finally with the alloantiserum or by sequential absorption with affinity columns of Sepharose 4B coupled to the antibodies. The three antigens which were sequentially isolated with the mAb 118, 3, and 155, respectively, were analysed by SDS-PAGE after digestion with Staphylococcus aureus V8 protease, and they showed differences in peptide patterns. The relative amounts of the antigens expressed on red blood cells and on lymphocytes were different based on the results of sequential isolation and indirect cellular radioimmunoassay: the antigen which reacted with both mAb 3 (and 56 or 60) and 155 was the major class I antigen on red blood cells, and the antigen which reacted with mAb 118, 3 (and 56 or 60) and 155 was the major class I antigen on lymphocytes.