Measurement of ligand-induced activation in single viable T cells using the lacZ reporter gene.
We have used the bacterial beta-galactosidase gene (lacZ) as a reporter gene for the rapid measurement of T-cell antigen receptor (TCR)-mediated activation of individual T cells. The reporter construct contained the lacZ gene under the control of the nuclear factor of activated T cells (NF-AT) element of the human interleukin 2 enhancer [Fiering, S., Northrop, J. P., Nolan, G. P., Matilla, P., Crabtree, G. R. & Herzenberg, L. A. (1990) Genes Dev. 4, 1823-1834]. The activity of the intracellular lacZ enzyme was analyzed by flow cytometric measurement of fluorescein accumulation in cells loaded with the fluorogenic beta-galactosidase substrate fluorescein di-beta-D-galactopyranoside. As a model system, the T-cell hybridoma BO4H9.1, which is specific for the lysozyme peptide (amino acids 74-88)/Ab complex, was transfected with the NF-AT-lacZ construct. lacZ activity was induced in 50-100% of the transfectant cells following exposure to pharmacological agents, to the physiological peptide/major histocompatibility complex ligand, or to other TCR-specific stimuli. Interestingly, increasing concentrations of the stimulus increased the fraction of lacZ+ cells, but not the level of lacZ activity per cell. Even under widely varying levels of stimulus, the level of lacZ activity in individual lacZ+ cells remained within a remarkably narrow range. These results demonstrate that TCR-mediated activation can be readily measured in single T cells and strongly suggest that, once committed to activation, the level of NF-AT transcriptional activity in individual T cells is independent of the form or concentration of stimulus. This assay is likely to prove useful for the study of early activation events in individual T cells and of TCR ligands.
Karttunen
J
J
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Shastri
N
N
D000818:Animals; D002460:Cell Line; D004306:Dose-Response Relationship, Immunologic; D004742:Enhancer Elements, Genetic; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D008024:Ligands; D008213:Lymphocyte Activation; D051379:Mice; D009113:Muramidase / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D012045:Regulatory Sequences, Nucleic Acid; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology*; D001616:beta-Galactosidase / Q000235:genetics
D008024:Ligands; D011948:Receptors, Antigen, T-Cell; D009113:Muramidase; D001616:beta-Galactosidase