title: Direct effects of a monoclonal B cell differentiation factor and of purified interleukin 1 on B cell differentiation.
abstract: We have previously described the presence of factors in mixed lymphocyte culture supernatants that induce activated but not resting human B cells to secrete Ig. In the present study, we describe the effects of a B cell differentiation factor in the supernatant (SN) of a T-T hybridoma (clone 7D5). We find that it induces Ig secretion by human B cells in the absence of T cells or monocytes. It acts only on activated B cells, because small (resting) B cells isolated by centrifugal counterflow elutriation do not respond to it, whereas the same cells do develop into Ig-secreting cells if activated in culture with Staphylococcus aureus Cowan I before exposure to SN 7D5. By using class-specific reagents in enzyme-linked immunosorbent assays, we found SN 7D5 to result in the secretion of significant amounts of IgM, IgG, and IgA. We also studied the effects of highly purified interleukin 1 on this differentiation process. Interleukin 1 by itself failed to induce Ig secretion by activated B cells, and its presence was not required for the induction of Ig secretion by SN 7D5. However, interleukin 1 consistently synergized with SN 7D5 in inducing Ig secretion by purified B cells.
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation; D006133:Growth Substances / Q000502:physiology*; D006801:Humans; D007126:Immunoglobulin Allotypes / Q000096:biosynthesis; D007375:Interleukin-1 / Q000502:physiology*; D015847:Interleukin-4; D007399:Interphase; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000502:physiology*
chemical_list: D006133:Growth Substances; D007126:Immunoglobulin Allotypes; D007375:Interleukin-1; D008222:Lymphokines; D015847:Interleukin-4