REGULATION OF MURINE B-CELL THY-1 EXPRESSION BY IL-4, IFN-GAMMA, AND CD4+ T-CELL SUBSETS

Interleukin 4 (IL-4) induces the expression of membrane Thy-1 on the vast majority of lipopolysaccharide (LPS)-stimulated normal murine B cells in vitro. This induction is inhibited by interferon-gamma (IFN-γ). IL-4 and IFN-γ are required late in culture to effect maximal induction and inhibition of Thy-1 expression by LPS- or LPS + IL-4-stimulated B cells, respectively. IFN-γ suppresses IL-4-induced Thy-1 expression by inhibiting the induction of steady-state levels of Thy-1-specific mRNA. Three distinct CD4+ Th2 clones, through their release of IL-4, induce B cells to express high levels of Thy-1, by 24 hr, in striking contrast to the 3 days required to induce Thy-1 expression after stimulation with LPS and IL-4. This induction is abrogated by the addition of IFN-γ. B cells stimulated with three distinct Th1 clones (IFN-γ- and IL-2-producing) exhibit a modest, non-IL-4-dependent, expression of Thy-1. In contrast to intrinsic expression of Thy-1 by Th2-stimulated B cells, Thy-1 expressed by Th1-stimulated B cells is acquired, having the allotype specificity of the stimulating T cell. © 1990.