The MHC class II-restricted T cell response of C57BL/6 mice to human C-reactive protein: Homology to self and the selection of T cell epitopes and T cell receptors

Abstract

The T cell response of C57BL/6 mice to human C-reactive protein (hCRP), an inducible acute phase protein, was analysed. Two I-A b-restricted epitopes at positions 79–95 (epitope A) and 87–102 (epitope B) were identified using a panel of CD4 + T cell clones. Human C-reactive protein shares considerable homology with mouse C-reactive protein and mouse serum amyloid P component. Interestingly, the two epitopes map to the region of lowest homology between human CRP and its mouse homologues. Human CRP-specific T cell clones express a restricted T cell receptor (TCR) repertoire, both with regard to usage of TCR germline gene segments (Vα, Jα, Vβ, Jβ) and certain TCR αβ combinations. Therefore, epitope-A specific clones preferentially use TCR Vβ8.3 and Vα3-Jαl5-Vβ8.3-Jβ2.3 and epitope-B specific clones use Vβ2 and Vα1-Jα24/30-Vβ2. This bias is even more pronounced when TCR usage is correlated with epitope fine specificity. A role for homology of hCRP to self components in selecting these particular T cell epitopes and TCR is discussed.