T cell recognition of lysozyme. II. Shift in specificity during long-term culture determined by synthetic overlapping peptides comprising the entire protein chain.

Recently, by using a comprehensive synthetic strategy developed in this laboratory, we localized four sites (T sites) within the polypeptide chain of lysozyme recognized by T cells from two high responder mouse strains, DBA/1 and B10.BR. However, to detect minor specificities, the selective enrichment of lysozyme reactive cells, would be required. T cells from long-term cultures maintained by repeated stimulation with antigen are selectively enriched for that antigen. It is not known whether maintaining T cells for extended periods of time in vitro has any consequences on the profile of T cell recognition. In the present study, T cells from long-term cultures, derived from these two high responder lysozyme-primed mouse strains, were examined for their responsiveness to a series of synthetic overlapping peptides encompassing the entire polypeptide chain of the lysozyme molecule. We have found that the profile of T cell recognition of the long-term cultures may not reflect that of the lysozyme primed lymph node cells, but that it is subject to a shift in specificity towards submolecular features of the molecule. In addition, we have identified in B10.BR mice another region within the polypeptide chain of lysozyme (residues 72-84) which may potentially harbor a previously undetected (in lymph node cells) minor T site.