Degenerate MHC restriction reveals the contribution of class I MHC molecules in determining the fine specificity of CTL recognition of an immunodominant determinant of HIV-1 gp160 V3 loop.
The novel allogeneic presentation of an immunodominant determinant within the HIV-1 gp160 V3 loop by three different class I MHC molecules to the same CD8+ CTL is used to study the influence of the MHC molecule on the fine specificity of CTL recognition. We previously reported that four distinct class I molecules of H-2d,u,p,q presented the V3 decapeptide P18-I10 (RGPGRAFVTI) to CTL. Surprisingly, we found that H-2d,u,p cells mutually cross-present the P18-I10 peptide to allogeneic CTL clones of each of the other haplotypes, whereas none of these cross-presents to H-2q CTL, nor do H-2q targets present to CTL of the other haplotypes. Here, we explore the critical amino acid residues for the cross-presentation using 10 variant peptides with single amino acid substitutions. The fine specificity examined using these mutant peptides presented by the same MHC class I molecule showed striking similarity among the CTL of each haplotype, expressing either V beta 8.1 or V beta 14. In contrast, the fine specificity is different between the distinct MHC class I molecules even for the lysis by the same CTL, as shown by reciprocal effects of the same substitutions. Thus, peptide fine specificity of a single TCR is influenced by changes in the class I MHC molecules presenting the Ag.
Shirai
M
M
Metabolism Branch, National Cancer Institute, Bethesda, MD 20892, USA.
Kozlowski
S
S
Margulies
D H
DH
Berzofsky
J A
JA
D000818:Animals; D006183:H-2 Antigens / Q000737:chemistry / Q000502:physiology*; D019302:HIV Envelope Protein gp160 / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D016056:Immunodominant Epitopes / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D006183:H-2 Antigens; D019302:HIV Envelope Protein gp160; D016056:Immunodominant Epitopes