In vitro synthesis of IgE by human lymphocytes. I. The spontaneous secretion of IgE by B lymphocytes from allergic individuals: a model to investigate the regulation of human IgE synthesis.

In view of the controversial data in the literature regarding the in vitro IgE synthesis by human lymphocytes, the conditions for culture of lymphocytes and the methodology for measurement of the IgE produced are described in detail. In the absence of any added mitogen, enriched B cell preparations derived from 70% of allergic donors actively secreted 100 to 3200 pg/ml of IgE after culture for 7 days, at which time the cell viability was higher than 85%. In comparable B cell cultures derived from non-allergic donors, only trace amounts of de novo synthesized IgE were detected in 20% of the cases. All B cell cultures actively secreted IgG, IgA, IgM and there was no apparent relationship between the secretion of IgE and that of the other classes of Ig. By contrast, the synthesis of IgE by unfractionated peripheral blood mononuclear cells of allergic individuals, which were stimulated with pokeweed mitogen (PWM) under several experimental conditions, was not consistently reproducible, i.e. the spontaneous synthesis of IgE in such cultures was either suppressed or enhanced by PWM. The most important finding was that the secretion of IgE was selectively enhanced by supplementing the B cell cultures with cell-free supernatants (CFS) of cultures of neonatal lymphocytes which had been preincubated with 10 micrograms/ml IgE. It is, therefore, concluded that B cell cultures from allergic individuals constitute an appropriate model for investigations of the mechanisms underlying the regulation of human IgE synthesis.