Rabbit antipeptide antibodies against restricted domains of the histocompatibility complex

The work reported here concerns the specificity of four antibodies elicited by synthetic peptides corresponding to three domains of the HLA-B7 glycoprotein, and one of the beta 2 microglobulin. One of the four peptides had been previously investigated, but the data obtained by its elicited antibodies were uncomplete. Of the three HLA-B7 peptides assayed, one was unable to raise an immune response. The other two produced antibodies in good titer that reacted with the antigen peptide, but were unable to recognize antigenic determinants when tested on membrane glycoproteins solubilized from human lymphoblastoid cells. In contract, the antibody elicited by the only fragment from the beta 2microglobulin recognized the native beta 2microglobulin molecule as well as HLA/beta 2m complexes, and reacted with intact human cells, as determined by ELISA and by FACS analysis. This peptide, which contains one of the most hydrophylic fragment of the whole molecule, is likely an important antigenic site, since it is also recognized by traditional antisera raised against native beta 2microglobulin.