Inhibition of the T-cell receptor-mediated signal transduction by microinjection of anti-Lck monoclonal antibody into T-cells.
Engagement of T-cell receptor (TcR)/CD3 complexes on T-cells rapidly provokes tyrosine phosphorylation of cellular proteins, which is thought to be an essential step to the following events of T-cell activation. p56lck, a member of src-related, non-receptor type protein tyrosine kinases, is expressed predominantly in lymphocytes. Accumulating data suggest that p56lck is one of the kinases responsible for TcR-mediated protein tyrosine phosphorylation. To investigate the role of p56lck in TcR-signaling in detail, we injected anti-Lck monoclonal antibody (mAb), MOL171 or MOL294, both specifically suppress Lck kinase activity in vitro, into Jurkat T-cells by the erythrocyte-ghost procedure in order to block the activity of p56lck. In Jurkat cells injected with anti-Lck mAb, intracellular Ca2+ mobilization induced by TcR-stimulation was markedly reduced in comparison with control mouse IgG-injected samples. This block of Ca2+ influx seems to be specific for TcR-signaling because anti-Lck mAb-injection did not cause significant suppression of phytohaemagglutinin-induced Ca2+ increase. Furthermore, injection of anti-Lck mAb inhibited TcR-mediated protein tyrosine phosphorylation of 100 kDa protein and phospholipase C gamma 1. These results confirm that p56lck is an indispensable element of TcR-signaling and p100 and phospholipase C gamma 1 are strongly presumed to be candidates for substrates for p56lck.
Nakamura
K
K
Department of Immunology, Kyushu University, Fukuoka, Japan.
Koga
Y
Y
Yoshida
H
H
Tanaka
K
K
Sasaki
M
M
Kimura
G
G
Nomoto
K
K
D000911:Antibodies, Monoclonal / Q000276:immunology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004910:Erythrocyte Membrane; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008845:Microinjections; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D014443:Tyrosine / Q000378:metabolism
D000911:Antibodies, Monoclonal; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D002118:Calcium