IL-3 IN COMBINATION WITH IL-4, INDUCES THE EXPRESSION OF FUNCTIONAL CD1 MOLECULES ON MONOCYTES

CD1 molecules have recently been shown to present bacterial antigens t o CD4(-)CD8(-)TCR alpha beta(+) T lymphocytes. The expression of CD1 o n monocytes can be induced by GM-CSF and is further enhanced by IL-4. GM-CSF and IL-3 receptors share a common chain and often have similar activities; however, only IL-3, but not GM-CSF, can stimulate CD4(-)CD 8(-)TCR alpha beta(+) T lymphocytes directly, In this study we show th at IL-3, in combination with IL-4, can also induce the expression of C D1 on monocytes to a level comparable to that induced by GM-CSF/IL-4. This induction of CD1 by IL-3 can be suppressed by IL-10. Furthermore CD1-induced antigen presentation was similar whether CD1 was induced b y IL-3/IL-4 or GM-CSF/IL-4. The ability of IL-3 to induce expression o f CD1 molecules and to directly stimulate CD4(-)CD8(-) alpha beta(+) T CR T lymphocytes raises interest in the role of this cytokine in the d evelopment, differentiation and function of this T cell subset. (C) 19 96 Academic Press Limited