IL‐6 reveals an intrinsic polyspecific phenotype of the HEL T cell repertoire in BALB/c mice

The T cell repertoire raised by immunization with hen egg lysozyme (HEL) in H‐2 d mice has been well characterized by proliferation studies, as presenting a single dominant determinant (peptide108–116) and 2 subdominant determinants (p11–25 and p20–35). T cells directed to other areas on the molecule do not arise after HEL‐CFA immunization as detected in a pepscan by proliferation and, in our hands, by ELISAspot assays. In previous experiments, IL‐6 had been shown to alter the hierarchy of peptide responses to HEL (Drakesmith et al, PNAS, 2000). We therefore immunized BALB/c mice with a CFA emulsion containing HEL with recombinant IL‐6 (or HEL‐CFA co‐immunized with an adenovirus vector containing IL‐6) to ask which T cells would be primed that could be recalled in vitro by a panel of overlapping 15 aa peptides all across the HEL molecule. IL‐6 plus HEL induced co‐dominant responses recalled by pepscan peptides in the regions 103–121, 67–85 as well as 87–103, as measured by proliferation and ELISAspot. Other, weakly subdominant determinants were also detected by proliferation and cytokine analysis in distinct areas: 9–25, 27–45, 37–51 and 47–61. Surprisingly, immunization with p61–85 primed for a response to p106–120 as well as to HEL. T cell hybrids generated after immunization with p106–120 and selected on the basis of reactivity to HEL, confirmed these results in that crossreactive responses to 106–120, 85–101 and 67–85 regions were displayed by public T cell clones. This phenomenon may be more frequent than previously imagined, and in this case extended to three determinants on the same molecule. Such polyspecific clones may achieved dominance owing to their polyreactive phenotypes. In conclusion, the inherent degenerate recognition of particular T cells can be revealed during inflammatory processes upregulated by agents such as IL‐6. Grant support NIH R0142396