Distinct signals are required for proliferation and lymphokine gene expression in murine T cell clones

S. E. Heckford, E. P. Gelmann, C. L. Agnor, S. Jacobson, S. Zinn, L. A. Matis

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Experiments were performed to assess the capacity of lectin (Con A), ionomycin, phorbol ester (PMA), and recombinant IL 2 to mediate proliferation as well as the expression of cell surface IL 2 receptors, two lymphokine genes, IL 2 and IFN-γ, and the c-myc proto-oncogene in cloned T cell populations. Stimulation of T cell clones with recombinant IL 2 resulted in proliferation and sustained expression of the c-myc cellular proto-oncogene, but did not induce the expression of mRNA for the lymphokines IFN-γ and IL 2. In contrast, stimulation of cloned T cells with lectin alone induced significant IFN-γ and IL 2 mRNA expression, up-regulation of the number of cell surface IL 2 receptors, and transient c-myc expression. Ionomycin alone was not a sufficient signal for lymphokine mRNA induction. The phorbol ester PMA alone induced neither proliferation nor lymphokine gene expression but potentiated lectin and ionomycin-mediated signals. We also performed experiments to examine whethe the T cell response to extracellular stimuli was a function of the activation state of the cell. Reexposure of 48-h antigen-activated cloned cells to identical stimuli revealed several differences. 1) Low but significant levels of IFN-γ mRNA were now also reinduced in activated clones cells in response to IL 2 or PMA alone, 2) Activated cells were refractory to reinduction of IL 2 mRNA by any stimulus, which may reflect a physiologic mechanism to limit clonal expansion after antigenic stimulation. This could be partially reversed by restimulation with lectin in the presence of cycloheximide, suggesting a role for a labile protein repressor in the down-regulation of IL 2 mRNA expression. 3) PMA alone induced an IL 2-independent proliferation response. We demonstrate that distinct signals are required for lymphokine gene expression vs cellular proliferation in cloned T lymphocyte populations, and that the capacity of extracellular stimuli to reinduce expression of lymphokine genes or to mediate cell proliferation is altered by prior activation.

Original languageEnglish (US)
Pages (from-to)3652-3663
Number of pages12
JournalJournal of Immunology
Volume137
Issue number11
StatePublished - 1986
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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