Modeling of early events in T cell signal transduction after controlled T cell activation by peptide major histocompatibility complex.
Calcium signaling was observed in murine T cells over time, starting at a precise moment of contact with a layer of fibroblasts expressing a stimulatory major histocompatibility class II-peptide complex. The contact was controlled by a film-thinning apparatus. Intracellular calcium levels were followed with the ratiometric dye, Fura-2. The calcium response was highly synchronized and well fitted by a mathematical model. The model includes three components: a sequence of reactions occurring after T cell receptor (TCR) triggering; InsP3-mediated calcium release from intracellular stores (Meyer and Stryer, Proc. Natl. Acad. Sci. USA 85: 5051-5055, 1988); and slow changes in levels phospholipase C-gammal (PLCgammal) reflecting a decrease in receptor triggering rate. Each component in the model controls a different part of the response-the initial delay, the sharp rise, and the slow decay, respectively. Kinetic parameters determined from curve fitting were the initial delay in calcium signaling defined as the time when [PLCgammal] reached its half of its maximum (76 s), the coefficient characterizing calcium efflux from endoplasmic reticulum (ER) (2.86 microM s(-1), expressed per liter of cell volume), and a rate constant characterizing the diminishing yield of production of PLCgammal (0.00046 s(-1)) by active TCR. Only the parameter representing PLCgammal production varied much from cell to cell.
Kim
S
S
Department of Chemical Engineering and Applied Chemistry, Columbia University, New York, NY 10027, USA.
Patrick
S M
SM
Braunstein
N S
NS
Thomas
J L
JL
Leonard
E F
EF
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D001698:Biomedical Engineering; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D020013:Calcium Signaling; D002460:Cell Line; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism; D006825:Hybridomas / Q000276:immunology / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D051379:Mice; D008954:Models, Biological; D051966:Phospholipase C gamma; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D007527:Isoenzymes; D011948:Receptors, Antigen, T-Cell; D010738:Type C Phospholipases; D051966:Phospholipase C gamma