The Qa-1 alloantigens. II. Evidence for the expression of two Qa-1 molecules by the Qa-1d genotype and for cross-reactivity between Qa-1 and H-2K.
The nature of cell surface determinants detected by Qa-1-specific alloantisera and cytotoxic T lymphocytes (CTL) in mice of the H-2f, Qa-1d genotype was investigated. The H-2f, Qa-1d strains A.CA and B10.M express both Qa-1a and Qa-1b encoded alloantigenic determinants (Qa-1.1 and Qa-1.2, respectively), as defined in the prototypic A (or B6-Tlaa) and C57BL/6 (or A-Tlab) strains, respectively. Both anti-Qa-1.1 and -Qa-1.2 sera immunoprecipitate 46K m.w. glycoproteins from H-2f, Qa-1d strains. In addition to 46K m.w. proteins, anti-Qa-1.1 sera, but not anti-Qa-1.2 sera, precipitate 55 to 75K m.w. proteins; the nature of these proteins and their relationship to Qa-1 is unclear at present. Sequential immunoprecipitation experiments and the analysis of several recombinant strains revealed that anti-Qa-1.1 sera also cross-react with a 46K m.w. H-2f-encoded alloantigen, probably H-2Kf. Both Qa-1.1 and the non-Qa-1.1 cross-reacting determinants were detected by polyclonal anti-Qa-1a CTL on the Qa-1d strains. The Qa-1a encoded but not the cross-reacting determinants were detected by a cloned anti-Qa-1a CTL line. Sequential immunoprecipitation experiments on the recombinant strains B6.AC2 and B10.M(17R), which are Qa-1d but not H-2Kf, revealed that the Qa-1.1 and Qa-1.2 determinants do not reside on the same molecule. Furthermore, although Qa-1b-encoded determinants were detected on these strains with anti-sera and with bulk CTL cultures, cloned anti-Qa-1b CTL lines thus far analyzed have failed to react with Qa-1d targets, indicating that some but not all of the prototypic Qa-1b-encoded determinants are expressed by the Qa-1d strains.
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics*; D011232:Chemical Precipitation; D003429:Cross Reactions; D003601:Cytotoxicity Tests, Immunologic; D005838:Genotype; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology*; D006649:Histocompatibility Antigens / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D015395:Histocompatibility Antigens Class I; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic
D000954:Antigens, Surface; D006183:H-2 Antigens; D006649:Histocompatibility Antigens; D015395:Histocompatibility Antigens Class I; C032907:Q surface antigens