Regulation of Qa-1 expression and determinant modification by an H-2D-linked gene, Qdm.
We examined the regulation of cell surface expression of the Qa-1 alloantigens using a panel of monoclonal anti-Qa-1 cytotoxic T-lymphocyte (mCTL) lines. In contrast to previous reports of tissue-specific expression, we found that Qa-1 was widely expressed, resembling the prototypical class I H-2K/D molecules. We further found that an H-2D-linked gene, which we termed Qdm for Qa-1 determinant modifier, controlled expression of certain CTL-defined Qa-1 antigenic determinants. H-2Dk homozygous haplotypes expressed a recessive allele of the modifier, Qdmk, whereas all other H-2 haplotypes tested expressed a dominant allele, Qdm+. The Qdm+ allele regulated in trans Qa-1 epitope expression from a Qdmk chromosome, modifying expression of particular CTL-defined Qa-1 antigenic determinants rather than affecting levels of cell surface expression. Mechanisms of Qdm function may include either a novel protein modification system or an unprecedented case of antigen recognition restricted by a nonclassical major histocompatibility complex molecule.
Aldrich
C J
CJ
Department of Microbiology and Immunology, Baylor College of Medicine, Houston, TX 77030.
Rodgers
J R
JR
Rich
R R
RR
D000818:Animals; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D000939:Epitopes; D005786:Gene Expression Regulation; D005805:Genes, MHC Class I; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D006183:H-2 Antigens / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D051379:Mice / Q000235:genetics*; D008815:Mice, Inbred Strains; D010455:Peptides / Q000235:genetics; D014018:Tissue Distribution
D000939:Epitopes; D006183:H-2 Antigens; D015395:Histocompatibility Antigens Class I; D010455:Peptides; C032907:Q surface antigens; C090580:Qdm protein, mouse