Independent regulation of B-cell inducing factor and IL-2 production by T lymphocytes, and direct and indirect promotion of immunoglobulin secretion by glucocorticosteroid.
The conditions for induction of B-cell inducing factor (BIF) by human peripheral blood T cells was investigated. BIF was assayed by induction of immunoglobulin secreting cells (ISC) in peripheral blood B (non-T) cells stimulated with Staphylococcus aureus bacteria strain Cowan I (Sac), and in the IgM cell line SKW6.4. Maximum BIF production occurred with high concentrations of the T-cell mitogens phytohemagglutinin, concanavalin A, and PWM. Dexamethasone (Dex) also induced BIF production in T cells at 10(-5) to 10(-7) M. At 10(-5) and 10(-6) M Dex, the T-cell supernatants had to be dialyzed before testing because Dex alone stimulated variable levels of ISC in both test B-cell assays. Dex did not enhance BIF production by T cells that were optimally stimulated by lectin. BIF levels were maximum by Day 2 of T-cell cultures and remained high at Days 3 and 4. In contrast, IL-2 reached a peak at Day 1 and declined drastically by Day 4. We previously showed that IL-2 at less than 100 U/ml did not induce ISC in B cells and did not alter ISC induction by BIF. Dex did not induce IL-2 production and inhibited IL-2 production induced by Con A, in contrast to the promoting effects of Dex on BIF production, providing further evidence for the independence of BIF and IL-2 production and B-cell stimulation.
D000328:Adult; D001402:B-Lymphocytes / Q000378:metabolism*; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D006133:Growth Substances / Q000096:biosynthesis*; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis*; D015847:Interleukin-4; D037102:Lectins / Q000494:pharmacology; D008211:Lymphocyte Cooperation / Q000187:drug effects; D008222:Lymphokines / Q000096:biosynthesis*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
D006133:Growth Substances; D007376:Interleukin-2; D037102:Lectins; D008222:Lymphokines; D015847:Interleukin-4; D003907:Dexamethasone