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Background Comparable T cell-containing and T cell-depleted culture systems for human IgE synthesis arc currently not available. Objective This has prompted us to develop peripheral blood mononuclear cell (PBMC) based culture systems for human IgE synthesis in the presence and absence of T cells. Methods In this paper we describe simplified conditions for in vitro synthesis of high levels of IgE by human peripheral blood B cells, both in T cell-containing cultures and in anti-CD40 stimulated T cell-depleted cultures. Results T cell-depleted cultures released approximately 20 times more IgE [range 4I0-2220ng/mL (mean 1270 ng/mL); based on six experiments using cells from three donors] than did T cell-containing cultures [range 23-105 ng/mL (mean 58ng/mL); based on 15 experiments using cells from three donors]. Reconstitution experiments were performed lo investigate the role of T cells on IgE synthesis. Adding T cells back to the anti-CD40 stimulated T cell-depleted cultures resulted in a dose-dependent inhibition of IgE production. In the absence of anti-CIMO low numbers of T cells stimulated, while high numbers suppressed, IgE production: the optimal ratio of T cells to non-T cells for maximal IgE production was found to be 1:1. At this ratio, irradiated (non-replicating) T cells supported a much greater IgE synthesis than did non-irradiated T cells. Conclusion The development of these systems provides directly comparable T cell-containing and T cell-depleted cultures for human IgE synthesis from peripheral blood, allowing further study of the role of T cells in IgE regulation. These systems will also be of use for determining whether potential modulators of IgE synthesis act on the T cells or on other cell types. [ABSTRACT FROM AUTHOR]