Ca2+ response in single human T cells induced by stimulation of CD4 or CD8 and interference with CD3 stimulation.
A Ca2+ imaging method has been used to demonstrate simultaneously the magnitude and time course of the increase in the intracellular Ca2+ concentration ([Ca2+]i) in 10-30 individual human peripheral T cells following stimulation by anti-CD4 or anti-CD8 monoclonal antibody (MAb) as well as anti-CD3 MAb. The rise in [Ca2+]i began within 10 s of the introduction of the MAb and reached a peak of 240 nM (mean of 73 cells) in 20-40 s. The peak was followed by a slow decrease persisting for 6-8 min. Comparing Ca2+ responses in the presence and absence of external Ca2+, the rise in [Ca2+]i was found to be caused by both transient intracellular Ca2+ release and a long-lasting Ca2+ influx from outside the cell. Cross-linking of CD4 or CD8 using anti-IgG antibody augmented the response in individual cells, as seen in the higher peak (365-390 nM) and the longer duration (over 10 min). Simultaneous stimulation of CD3 and CD4 did not cause a summation of Ca2+ responses but caused a suppression in the CD3-mediated Ca2+ response. The results support the view that CD4 and CD8 play a role in signal transduction for T cell activation and that the CD4-derived signal interferes with the CD3-derived signal at some stage in the signalling pathway causing the Ca2+ response.
Katayama
Y
Y
Department of Physiology, Tokyo Women's Medical College, Japan.
Miyazaki
S
S
Oshimi
Y
Y
Oshimi
K
K
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D002118:Calcium / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000502:physiology; D015398:Signal Transduction / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D004533:Egtazic Acid; D002118:Calcium