Correlation of Qa-1 determinants defined by antisera and by cytotoxic T lymphocytes

Abstract

Cytotoxic T lymphocytes (CTL) activated in H-2 identical, Qa-1 disparate mixed leukocyte cultures recognize H-2-nonrestricted target antigens indistinguishable by strain or tissue distribution from serologically defined Qa-1 antigens. Cloned Qa-1-specific CTL define determinants encoded by four Qa-1 genotypes; we used anti-Qa-1 sera in antibody blocking experiments to determine if these determinants reside on molecules recognized by Qa-1-specific antibodies. Antisera containing Qa-1.1-specific and TL-specific antibodies blocked recognition of two CTL-defined determinants associated with Qa-1a. Although both Qa-1 and TL molecules are expressed on activated T cells from appropriate strains, our studies indicated that the CTL recognized Qa-1, not TL. In addition, anti-Qa-1.2 serum inhibited CTL recognition of Qa-1b- and Qa-1c-encoded determinants. Qa-1d target cells are unique in that they express determinants recognized by anti-Qa-1a CTL and by anti-Qa-1b CTL. Killing of Qa-1d targets by anti-Qa-1a CTL was not inhibited by anti-Qa-1.1 serum, but was partially inhibited by anti-Qa-1.2 serum. Cytotoxicity of Qa-1d cells by one anti-Qa-1b CTL clone was inhibited by both anti-Qa-1.2 and anti-Qa-1.1 sera, indicating close association of both serological determinants with the determinants recognized by the CTL. Thus, all of the CTL-defined Qa-1 determinants resided on molecules recognized by Qa-1-specific antibodies, but anti-Qa-1a CTL and Qa-1.1-specific antibodies did not have identical specificities.

A fail-safe mechanism for maintaining self-tolerance.

“…Fig. 1 a shows that unprimed B6' mice (which are Qa-1 = [40]) generate very weak CTL responses to B6 (which are Qa-lb), and mice primed in vivo with B6 cells do no better ( Fig. 1 b).…”

Anti-STAT6 CTL activity inStat6−/−mice

“…Peptides were purchased from Genemed Synthesis. Flow cytometry analyses of CTL lines was performed as previously described 19 . using anti-CD4 antibody GK1.4 (PharMingen) and anti-CD8α antibody YTS169.4 (kindly provided by Dr. James Forman,) The CTL were CD8 + and CD4 − , as expected.…”

“…Using specific strain combinations as described, CTL were generated in secondary MLC as described 19 . Briefly, 5 × 10 6 responder and 5 × 10 6 irradiated (3000Rad) stimulator spleen cells were incubated for 6–7 d in RPMI 1640 supplemented with 7–10% fetal bovine serum, 1% L-glutamine and 50 ng/mL 2-mercaptoethanol at 37°C in 7% CO 2 .…”

The TL region gene 37 encodes a Qa-1 antigen.

“…The protein product in the Qa-1' strains is denoted as Qa-1.1, and that in Qa-111 strains as Qa-1.2. The Qa-1 molecules from Qa-1c and Qa-ld strains are very similar to Qa-1.2 as shown by serological, biochemical, and CTL analyses (12)(13)(14)(15)(16).…”

“…Subsequent biochemical studies revealed Qa-1 antigens to have structural properties characteristic of class I antigens, i.e., cell surface glycoproteins with molecular weight of -48,000 and associated with 02-microglobulin (9)(10)(11) . Four alleles (a,b,c,d) have been defined for the Qa-1 locus by CTL reactions (12)(13)(14)(15). The protein product in the Qa-1' strains is denoted as Qa-1.1, and that in Qa-111 strains as Qa-1.2.…”