EFFECTS OF ANTI-IL-4 RECEPTOR MONOCLONAL-ANTIBODY ON IN-VITRO T-CELL CYTOKINE LEVELS - IL-4 PRODUCTION BY T-CELLS FROM NONATOPIC DONORS

IL-4 is a pleiotropic cytokine which is involved in the development of atopic diseases, Only limited data exist on IL-4 production in humans , and the relative contribution to atopy of either unbalanced IL-4 pro duction, or increased IL4-responsiveness of target cells, is still unk nown. The use of a MoAb to the IL-4 receptor alpha-chain (IL-4R alpha) enabled us to demonstrate that IL-4 production in vitro is usually un derestimated, due to in vitro consumption, even in cultures of purifie d T cells. When IL-4 consumption was blocked, it became evident that C D80 and CD86 bath provide effective costimulatory signals for high IL- 4 production. Moreover, we found that even stimulation with a soluble antigen (tetanus toroid) induces IL-4 production by T cells from healt hy non-atopic donors. Both sets of data imply that IL-4 is not require d for IL-4 production by memory and/or effector T cells. Our data furt her show that endogenous IL-4 activity modulates IL-10 and interferon- gamma production by T cells in opposite directions. The use of this re ceptor-blocking antibody will thus be helpful for in vitro studies on IL-4 regulation. Consumption of IL-4 by different cell types during bl vitro cultures might have interfered with previous attempts to quanti fy IL-4 production by human T cells.