Human IL-10 reduces the number of IL-4-induced IgE B cells in cultures of atopic mononuclear cells.

Abstract

We investigated the effect of recombinant human IL-10 on IL-4- and antigen-driven human peripheral blood mononuclear cell cultures derived from atopic donors. These cultures were phenotyped for the percentage of B cell (CD20 HLA-DR) population by flow cytometry and for intracellular IgE using epifluorescence microscopy. The addition of IL-4 (100 U/ml) to these cultures resulted in an increase in the percentage of IgE B cells. However, the percentage of IgE B cells in cultures coincubated with IL-10 (2 or 20 ng/ml) and IL-4 was reduced to the level of medium control. Peripheral-blood mononuclear (PBMN) cultures driven with dust mite allergen demonstrated a significant increase in cellular proliferation, as measured by 3[H] thymidine uptake, and in the percentage of IgE B cells. The coaddition of IL-10 (2 or 20 ng/ml) to these cultures significantly inhibited both proliferation and the mean percentage of IgE B cells. The inhibitory effect of IL-10 on IgE B cell percentages in both the IL-4- and the allergen-driven cultures, and on allergen-driven proliferation, was dependent upon the presence of monocytes. Interestingly, the inhibitory effect of IL-10 on allergen-driven proliferation in the atopic PBMN cultures was reversible by the coaddition of exogenous IFN gamma (1 ng/ml) and IL-2 (2 U/ml). The addition of IL-2 (2 U/ml) partially reversed IL-10-inhibited allergen-driven proliferation while alone IFN gamma had no effect (1 ng/ml). In fact, the addition of IFN gamma (1 ng/ml) in the absence of either IL-10 or IL-2 (2 U/ml) partially inhibited allergen-driven proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)