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Differential expression of protein tyrosine kinases and their phosphorylation in murine Th1 cells anergized with class II MHC‐peptide complexes
Author(s) -
Yu Sheue Ching T,
Nag Bishwajit
Publication year - 1997
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1038/icb.1997.45
Subject(s) - fyn , t cell receptor , biology , mhc restriction , mhc class i , t cell , microbiology and biotechnology , phosphorylation , tyrosine phosphorylation , major histocompatibility complex , mhc class ii , antigen presentation , antigen , proto oncogene tyrosine protein kinase src , immune system , immunology
In resting T cell clones, antigen presentation with immobilized anti‐CD3 or anti‐T cell receptor (TCR) is known to result in a state of anergy as characterized by unresponsiveness to normal antigenic restimulation. Similarly, T cell unresponsiveness could be induced by immobilized (plate‐coated) complexes of purified class II MHC and antigenic peptide. It is not clearly defined whether the engagement of TCR by immobilized anti‐TCR or immobilized class II MHC‐peptide complexes generates similar or differential signals during the induction of T cell unresponsiveness. In order to address the initial signalling events induced by TCR occupancy with anti‐TCR and class II MHC‐peptide molecules, the expression of three critical protein tyrosine kinases (PTK) and their phosphorylation were investigated in the present study using a murine T cell clone (HS17) restricted for IA S and myelin basic protein (MBP (91–103)) peptide. The anergic T cells induced by immobilized IA S ‐MBP (91–103) complex or anti‐TCR (H57) showed differential expression of lck (56 kDa) and Zap‐70 (70 kDa) proteins. In both systems, however, the induction of T ceil unresponsiveness was accompanied by increased level of fyn (59 kDa) expression. When analysed for the total tyrosine phosphorylation of PTK. anergic HS17 T cells induced by both molecules showed increased phosphorylation associated with only the fyn protein. These results suggest that the signal transduction events induced by immobilized class II MHC‐peptide complexes and anti‐TCR are distinct, although both can initiate signals that lead to increased fyn expression and phosphorylation. In addition, the present study supports the evidence for the important functional association of fyn protein with direct TCR engagement in T cell signalling.