Establishment of CD4+ T cell clones specific to bovine beta-lactoglobulin and analysis of their specificity.

Abstract

Bovine beta-lactoglobulin (beta-LG) specific T cell clones, H1.1, 5G, 2.11G, and 6.11G were established from BALB/c mice and characterized. Surface phenotypes of clones were Thy1+, CD3+, CD4+, and CD8-. All clones recognize beta-LG in a I-Ad restricted manner. The T cell determinant region for H1.1 and 5G was identified as residues 42-56 of beta-LG by proliferation assay with overlapping synthetic peptides covering the entire sequence of beta-LG. The T cell determinant region for H1.1 was further delimited to residues 43-52 by using analog peptides. Previously we analyzed the T cell determinant regions of beta-LG in BALB/c, C3H/He, and C57BL/6 mouse by polyclonal T cell proliferation assay and reported that residues 42-56 of beta-LG constitute one of the major T cell determinants in BALB/c mice. Specificities of 2.11G and 6.11G were not identified by these synthetic peptides. Although reduction of disulfide bonds and CNBr cleavage of beta-LG did not affect the antigen recognition by 2.11G and 6.11G, tryptic degradation of the protein caused a clearer decrease of response in 6.11G than in 2.11G.