CD4 cross-linking (CD4XL) induces ras activation and tumor necrosis factor-α secretion in CD4+ T cells

Seetha M.Lakshmi Tamma, Narendra Chirmule, Hirosuka Yagura, Naoki Oyaizu, Vaniambadi Kalyanaraman, Savita Pahwa

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

CD4 molecules are the primary receptors for human immunodeficiency virus (HIV) and bind the envelope glycoprotein gp120 of HIV with high-affinity. We have previously shown that cross-linking of CD4 molecules (CD4XL) in normal peripheral blood mononuclear cells (PBMC) results in secretion of cytokines tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), but not of interleukin-2 (IL-2) or IL-4. To investigate the intracellular signaling events associated with CD4-gp120 interaction, we incubated CD4+ T cells from peripheral blood of HIV-negative healthy donors with HIV envelope protein gp160 alone or performed CD4XL with gp160 and anti-gp160 antibody. This procedure resulted in tyrosine phosphorylation of intracellular substrates p59(fyn), zap 70, and p95(vav) and also led to ras activation, as assessed by conversion of rasGDP to rasGTP. The role of ras in CD4 signaling was further investigated using CD4+ Jurkat cells transfected with a dominant negative ras mutant. CD4+ T cells expressing dn-ras secreted significantly reduced levels of TNF-α in response to CD4XL. These studies indicate that interaction of HIV gp160 with CD4 molecules activates the ras pathway in T calls, which may result in the cells becoming unresponsive to subsequent stimulation.

Original languageEnglish (US)
Pages (from-to)1588-1593
Number of pages6
JournalBlood
Volume90
Issue number4
DOIs
StatePublished - Aug 15 1997

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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