The choice between two distinct T cell determinants within a 23-amino acid region of lysozyme depends on their structural context.
The specificity of C57BL/6 T cells reactive to peptide aa 74-96 of hen egg-white lysozyme (HEL) was analyzed by using a panel of synthetic peptides of varying lengths from this region. It was found that peptide 74-96-reactive T cells induced by native HEL (aa 1-129) or its denatured fragment L2 (aa 13-105) recognized two distinct but overlapping determinants contained within aa 74-90 or aa 81-96, respectively. Peptide 74-96 itself induced both peptide 74-90-and peptide 81-96-specific T cells. Thus, a choice was made between these two potential T cell determinants on peptide 74-96, depending on which immunogen was used. Interestingly, the ability of both peptide determinants aa 74-90 and aa 81-96 to stimulate peptide 74-96-reactive T cells was partly dependent on the presence of residues within the overlap region (aa 81-90), suggesting that this region may play an important role in Iab-restricted T cell activation. This was further supported by the poor immunogenicity of shorter peptides 74-86 or 85-96, lacking residues from the overlap region in B6 mice. These two short peptides were nevertheless capable of eliciting T cell responses in B10.A mice, suggesting that the importance of this overlap region in obtaining a response to peptide 74-96 is related to the MHC haplotype.
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D000939:Epitopes; D005260:Female; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009113:Muramidase / Q000276:immunology; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology*
D000939:Epitopes; D010446:Peptide Fragments; D010047:Ovalbumin; D009113:Muramidase