ANALYSIS OF T-CELL RECEPTORS SPECIFIC FOR RECOGNITION OF CLASS-I(B) ANTIGENS

T cells that recognize a peptide presented by a self-class IA molecule generally use a restricted repertoire of Vbeta and Valpha receptors. In contrast, alloreactive T cells, which recognize alloantigens that p resent a wide array of peptides, use a diverse repertoire, particularl y in the CDR3 loop. Because the T cell repertoire directed against cla ss IB alloantigens is not known, we examined V-D-J sequences in Vbeta chains specific for Qa-1 and similar sequences in both Vbeta and Valph a chains specific for Qa-2. We observed that 14 Qa-1 -specific clones use a limited number of Vbeta segments and 8 of 14 express Vbeta8.2 an d have a conservation of charged residues in the CDR3 loop, particular ly between residues 99 and 101. Thirteen of the 14 clones rearrange to the second Jbeta cluster and use within this cluster is restricted. A lloreactive anti-Qa-1 T cells can be assigned into three different spe cificity groups based on a Qa-1 modifying gene, Qdm, as well as Qa-1 e pitope expression on Tap-2-deficient RMA-S cells. Receptors from membe rs of each specificity group are more similar in their CDR3 loop to ea ch other than members of the other groups. These data lend support to the Qa-1 class IB Ag presenting a limited number of peptides to T cell s or in some manner limiting the development of a diverse alphabeta ce ll repertoire. The alpha- and beta-chains from nine alloreactive anti- Qa-2 clones were analyzed. Vbeta use was limited to use of Vbeta7 or a member of the Vbeta8 family. Rearrangements were solely to the second Jbeta cluster. The use of Valpha and Jalpha segments were diverse. Al though conserved residues or motifs were observed in the CDR3 regions of both the beta- and alpha-chains, the extent of conservation was les s than that for anti-Qa-1 receptors. Anti-Qa-2 T cells can be divided into two specificities, Q6 and Q7. No common features were apparent be tween these groups.