Synthetic peptides and beta-chain gene rearrangements reveal a diversified T cell repertoire for a lambda light chain third hypervariable region.

Twelve L3T4+ Ly-2.2- subclones, derived from 4 independent BALB/c T cell lines, responded to a combination of the I-Ed molecule and a synthetic peptide corresponding to residues 91-108 of the lambda light chain from BALB/c myeloma protein M315 (alpha, lambda 2). Peptide analogues in which the mutated residues Arg95 or Asn96 were exchanged with the corresponding germ-line-encoded Ser95 or Thr96 had an abolished or greatly reduced capacity to stimulate T cell clones. However, responses of subclones to an analogue where the mutated Phe94 was substituted with the germ-line-encoded Tyr94 revealed three specificity patterns: 5 clones reacted only with the lambda 2(315) peptide, 6 clones responded equally well to both peptides and a single clone reacted better with the Tyr94 analogue. Analysis of the T cell receptor beta-chain gene rearrangements disclosed 7 distinct rearrangements, identical rearrangements only being found for subclones originating from the same line. At least 3 different V beta genes were used. Subclones with identical or nearly identical peptide specificity, major histocompatibility complex-restriction and alloreactivity could differ in their V beta or J beta gene segment utilization.