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Lack of evidence for aggregation‐dependent enhancement of p56 lck in the signal transduction upon major histocompatibility complex recognition by mature T cells
Author(s) -
Eshima Koji,
Suzuki Harumi,
Shinohara Nobukata
Publication year - 2002
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.2002.01392.x
Subject(s) - major histocompatibility complex , signal transduction , histocompatibility , microbiology and biotechnology , biology , antigen , immunology , human leukocyte antigen
Summary The kinase activity of lymphocyte‐specific tyrosine kinase p56 lck (Lck) upon physiological major histocompatibility complex (MHC) recognition by normal mature T cells was examined. Recognition of the target MHC molecules by T cells induced phosphorylation of the ζ‐chain without obvious enhancement of the background Lck activity. There was no sign of enhancement of Lck through putative T‐cell receptor (TCR)‐independent class II MHC/CD4 interactions either. As has been reported, cross‐linking of CD4 molecules by antibodies induced a marked enhancement of Lck activity. However, it did not have an immediate relevance to TCR‐mediated signal transduction, as judged from the lack of detectable de novo phosphorylation of ζ‐chain and the absence of functional responses of T cells. These results strongly favour the model in which TCR‐mediated signal transduction does not involve aggregation‐dependent enhancement of Lck, suggesting that the signal can be triggered simply by the recruitment of already active Lck with basal kinase activity through the formation of a TCR/MHC/CD4 ternary complex.