Subpopulations of circulating B cells and regulatory T cells involved in in vitro immunoglobulin E production in atopic patients with elevted serum immunoglobulin E.

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Abstract
The B lymphocyte subpopulations producing immunoglobulin (Ig)E and the regulatory T cells modulating this IgE production in normals, and in atopic patients with respiratory allergy, atopic dermatitis, and markedly elevated serum IgE levels (>5,000 ng/ml), were investigated. Peripheral blood lymphocytes (PBL) were separated into T and B cell fractions and the ability of B cells to produce IgE in the presence or absence of pokeweed mitogen (PWM) and/or T cells ws determined. The patients had a circulating population of cells which spontaneously produced up to 6 ng of IgE in vitro (per 4 X 10(5) non-E-rosetting cells) in the absence of T lymphocytes and PWM. PBL from normals did not possess such cells. This IgE synthesis occurred primarily (>75%) over the first 72 h of culture. There was a wide range in their activity between patients and from the same patient studied on repeated occasions (from <300 to 6,000 pg per culture). This spontaneous IgE production was inhibited by PWM (mean inhibition, 37%) or normal T lymphocytes (mean inhibition, 42%). The patients lacked T lymphocytes capable of inhibiting this spontaneous IgE synthesis in 7 of 13 experiments. Functionally distinct B cells were identified in the patients and normals that responded to PWM with IgE production in vitro and required T-helper cell activity. Patients had normal PWM-responsive B cell IgE biosynthetic activity and T-helper function for these B cells. Suppressor T cell activity for PWM-driven IgE synthesis was also evaluated. Both the normals' and the patients' T lymphocytes provided similar levels of T cell suppressor function for PWM-driven IgE production. Patients with elevated serum IgE possessed these inhibitory T cells at times when the T lymphocytes which suppressed spontaneous igE production were absent from their PBL.