Human peripheral blood monocytes release a 30,000 dalton factor (30 KD MF) that stimulates immunoglobulin production by activated B cells

J Immunol. 1985 Nov;135(5):3289-97.


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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism*
  • Cell Line
  • Growth Substances / metabolism*
  • Growth Substances / physiology
  • Hemolytic Plaque Technique
  • Humans
  • Immunoglobulin A / biosynthesis*
  • Interferon-gamma / pharmacology
  • Interleukin-2 / physiology
  • Interleukin-4
  • Kinetics
  • Leucine / analogs & derivatives
  • Leucine / pharmacology
  • Lymphocyte Activation*
  • Lymphocyte Depletion
  • Lymphokines / metabolism*
  • Lymphokines / physiology
  • Molecular Weight
  • Monocytes / drug effects
  • Monocytes / metabolism*
  • T-Lymphocytes
  • Trypsin / pharmacology


  • Growth Substances
  • Immunoglobulin A
  • Interleukin-2
  • Lymphokines
  • Interleukin-4
  • leucine methyl ester
  • Interferon-gamma
  • Trypsin
  • Leucine