Selective reactivity of CD8-independent T lymphocytes to a cytotoxic T lymphocyte-selected H-2Kb mutant altered at position 222 in the α3 domain
✍ Scribed by Sara E. Shepherd; Rui Sun; Stanley G. Nathenson; James M. Sheil
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 671 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
Abstract
To study the structural basis for specificity and affinity of cytotoxic T lymphocytes for major histocompatibility complex/peptide complexes, we have employed a cytotoxic T lymphocyte (CTL)‐mediated immunoselection approach to obtain H‐2K^b^ structural mutants which are resistant to lysis by a K^b^‐specific alloreactive CTL clone. In this study we describe the K^b^ structural mutant, designated R8.60.14, recovered following immunoselection using the CD8‐dependent CTL clone 60 as a selective agent. Although serologically unaltered with respect to K^b^ expression, R8.60.14 is not recognized by CD8‐dependent, K^b^‐specific CTL. DNA sequence analysis revealed a single Glu → Lys amino acid substitution at position 222 in the K^b^ α~3~ domain of this variant. To determine if a direct correlation exists between CD8 dependence of a K^b^ specific CTL and its failure to respond to R8.60.14, we examined the lytic response against R8.60.14 by CD8‐independent, K^b^‐specific CTL obtained from long‐term culture in the presence of anti‐CD8 monoclonal antibody, 3.155. CD8‐independent CTL exhibit no difference in their response against the R8 parent and R8.60.14 variant. This study demonstrates unequivocally that K^b^‐specific recognition of R8.60.14 by CD8‐independent CTL is unaltered, while the response by CD8‐dependent CTL is completely abrogated. Thus, the sole basis for emergence of this variant in the CTL‐mediated immunoselection approach used in this study resides in the alteration of a single CD8‐binding site residue at position 222 in the K^b^ α~3~ domain. The functional importance of this Glu^222^ residue for the interaction between the CD8 molecule on CD8‐dependent CTL and the K^b^ α~3~ domain is further reinforced by virtue of the recovery of the R8.60.14 variant on the basis of its resistance to lysis by a CD8‐dependent CTL clone in this CTL‐mediated immunoselection approach.