Analysis of the D-region products of H-2q using monoclonal antibodies reveals the expression of a new class I-like molecule.

To analyze how many D-region-encoded molecules could be detected in H-2q, we produced a panel of nine monoclonal antibodies from AKR (KkDk) anti-AKR.M (KkDq) immunizations. All of the Dq region antibodies cross-reacted on Dd and/or Ld, and all except one cross-reacted on Db, confirming the previously observed serologic and amino acid sequence homology between the D-region products of H-2d, H-2b, and H-2q. All of these monoclonal antibodies precipitated 46,000 dalton molecules from both cell-surface-labeled and biosynthetically labeled B10.AKM spleen cells, indicating that all were reactive with class I-like molecules. Sequential immunoprecipitation analysis with one of these antibodies, 66-3-5, reveals the presence of a previously unidentified class I-like molecule. Tryptic peptide map analysis reveals that this molecule may be the product of a newly described H-2Dq-region gene.