title: In vitro production of IgE-binding factors by human mononuclear cells.
abstract: This study documents the production of IgE-binding factors (IgE-BFs) by unstimulated and by mitogen-activated human mononuclear cells. IgE-BFs were detected by a sensitive radioimmunoassay employing monoclonal antibodies to lymphocyte Fc epsilon R (MabER). IgE-BFs were found in the 24-hr CSN of unfractionated tonsillar lymphocytes and of their B-cell but not of their T-cell enriched fractions. When cultured for 1 week, PBMC spontaneously synthesized and released IgE-BFs in the CSN; this was significantly reduced by IgE (10 micrograms/ml). PWM, PHA and Con A significantly increased the production of IgE-BFs by PBMC, and this was not influenced by IgE. The production of IgE-BFs in response to mitogens required interactions between T and non-T cells, and IgE-BFs seemed to be derived mainly from non-T cells. However, low levels of IgE-BFs could be detected in the CSN of highly purified T cells cultured for 1 week in the presence of PHA. The production of IgE-BFs by non-T cells was T-cell dependent and it was mediated by soluble factors released from mitogen-activated T cells. T-cell factors increased the secretion of IgE-BFs by: the macrophage cell line U937, adherent cells, and adherent cell-depleted B-cell preparations. It is concluded that the majority of IgE-BFs produced by cultured human mononuclear cells are derived from B cells and monocytes, and that their production is regulated by T lymphocytes.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D006801:Humans; D007962:Leukocytes / Q000276:immunology*; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis*; D008934:Mitogens / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D029584:Prostatic Secretory Proteins; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D008222:Lymphokines; D008934:Mitogens; D010835:Phytohemagglutinins; D029584:Prostatic Secretory Proteins; C043076:beta-microseminoprotein; C013059:immunoglobulin-binding factors