title: Human peripheral blood monocytes release a 30,000 dalton factor (30 KD MF) that stimulates immunoglobulin production by activated B cells.
abstract: Supernatants (SN) of well-washed adherent human monocytes, obtained from T cell-depleted peripheral blood mononuclear cells, contain a 30,000 dalton protein (30 KD MF) that increases immunoglobulin (Ig) synthesis by EBV-activated B cells two- to fourfold. This factor is released spontaneously during the first 20 hr after monocytes are placed in culture. SN containing 30 KD MF are inactive in the thymocyte co-stimulator assay, under conditions that will detect as little as 0.5 U of purified IL 1. The addition of autologous T cells to isolated adherent monocytes, previously depleted of T cells, suppresses the release or activity of this B cell stimulator in a dose-dependent manner. In addition, 30 KD MF stimulates a two- to fourfold increase in IgA production by cells of an EBV-transformed B cell line (JB/FF line) without increasing incorporation of [3H]thymidine. In contrast, stimulation of this B cell line with up to 10 U of purified IL 1 increases IgA synthesis by less than 50%, and addition of up to 100 U of recombinant IL 2 causes no change whatsoever in IgA production. However, co-stimulation with 30 KD MF and recombinant IL 2 or recombinant gamma-interferon induces more Ig production than is caused by the monocyte factor alone. These observations suggest that the monocyte, in addition to acting as an antigen-presenting cell and source of IL 1, facilitates B cell differentiation by producing a factor which acts both independently and in synergy with cytokines produced by T cells to stimulate Ig production by B lymphocytes.
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D006133:Growth Substances / Q000378:metabolism* / Q000502:physiology; D006462:Hemolytic Plaque Technique; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis*; D007371:Interferon-gamma / Q000494:pharmacology; D007376:Interleukin-2 / Q000502:physiology; D015847:Interleukin-4; D007700:Kinetics; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D008222:Lymphokines / Q000378:metabolism* / Q000502:physiology; D008970:Molecular Weight; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D013601:T-Lymphocytes; D014357:Trypsin / Q000494:pharmacology
chemical_list: D006133:Growth Substances; D007070:Immunoglobulin A; D007376:Interleukin-2; D008222:Lymphokines; D015847:Interleukin-4; C030365:leucine methyl ester; D007371:Interferon-gamma; D014357:Trypsin; D007930:Leucine