Synthetic peptides and β‐chain gene rearrangements reveal a diversified T cell repertoire for a λ light chain third hypervariable region

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Abstract
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 λ light chain from BALB/c myeloma protein M315 (α, λ2). 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 Tyr94revealed three specificity patterns: 5 clones reacted only with the λ2315 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 β‐chain gene rearrangements disclosed 7 distinct rearrangements, identical rearrangements only being found for subclones originating from the same line. At least 3 different Vβ genes were used. Subclones with identical or nearly identical peptide specificity, major histocompatibility complex‐restriction and alloreactivity could differ in their Vβ or Jβ gene segment utilization.