title: Developmental regulation of TCR-CD3-dependent [Ca2+]i responses of individual normal and pp59fyn-deficient T lymphocytes.
abstract: The aim of this study was to ascertain whether different types of T-cell receptor (TCR)-mediated [Ca2+]i signals could begin to explain the different cellular responses of mature and immature T cells to ligation of the TCR-CD3 complex. Using a digital fluorescence imaging system, we measured and compared [Ca2+]i of individual cells from immature and mature murine T-cell populations following application of CD3-epsilon monoclonal antibody (mAb). Our approach revealed distinctions among developmental subsets which were not seen by previous measurements of [Ca2+]i in bulk cell populations. The CD3-mediated [Ca2+]i responses of individual thymocytes were very complex. Latencies to peak [Ca2+]i varied greatly among thymocytes, but the responses of splenic T cells were synchronized, novel evidence that the timing of [Ca2+]i responses may be an important informative parameter for TCR-CD3 signalling. In addition, among cells responding to CD3 mAb, higher peak [Ca2+]i responses correlated with maturity (CD4+ CD8+ thymocytes < single-positive thymocytes < splenic T cells). Examination of cells from pp59fyn-deficient mice showed that pp59fyn deficiency affects the amplitude and probability, but not the latency or synchrony, of CD3-mediated [Ca2+]i responses of CD4+ CD8+ and CD4+ CD8- thymocytes. All subsets showed equivalent receptor-independent mobilization of [Ca2+]i. These developmentally distinct [Ca2+]i features most probably reflect meaningful developmental changes in how the TCR-CD3 complex couples to intracellular signalling machinery including pp59fyn. By clearly showing how [Ca2+]i responses change during development, these results support the hypothesis that distinctive types of [Ca2+]i responses drive thymocyte differentiation.
authors.affiliation: Department of Pharmacology, Mayo Foundation, Rochester, MN 55905, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Hedin
authors.forename: M W
authors.initials: MW
authors.lastname: Appleby
authors.forename: D E
authors.initials: DE
authors.lastname: Clapham
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D017252:CD3 Complex / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division; D002478:Cells, Cultured; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051076:Proto-Oncogene Proteins c-fyn; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013154:Spleen / Q000166:cytology; D016176:T-Lymphocyte Subsets; D013601:T-Lymphocytes / Q000378:metabolism*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D013950:Thymus Gland / Q000166:cytology
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D011518:Proto-Oncogene Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D013729:Terpenes; D019284:Thapsigargin; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D002118:Calcium