HUMAN INTERFERON-GAMMA ACTS AS A B-CELL GROWTH-FACTOR IN THE ANTI-IGM ANTIBODY COSTIMULATORY ASSAY BUT HAS NO DIRECT B-CELL DIFFERENTIATION ACTIVITY

  • 15 December 1986
    • journal article
    • research article
    • Vol. 137  (12) , 3861-3867
Abstract
In this study it is illustrated that recombinant human interferon-.gamma. (IFN-.gamma.) acts as a B cell growth factor (BCGF) in the anti-IgM antibody co-stimulatory assay. A monoclonal antibody that specifically inhibits the biological activities of IFN-.gamma. blocks its BCGF activity supporting the specificity of the IFN-.gamma. effect. Various IFN-.gamma. obtained from different sources displayed the same BCGF activity. Nonactivated B lymphocytes do not proliferate in response to IFN-.gamma.. IFN-.gamma. acts directly on B cells because highly purified B cells obtained after standard purification procedures coupled to cell sorting could still proliferate in response to IFN-.gamma.. Blood B lymphocytes were found to be more sensitive to the BCGF activity of IFN-.gamma. than B cells obtained from spleens or tonsils. The IFN-.gamma.-induced proliferation of B cells was short lasting when compared with that of recombinant IL 2 or BCGF containing T cell clone supernatants. B cells preactivated with either Staphylococcus aureus strain Cowan I (SAC) or optimal concentrations of anti-IgM antibodies coupled to beads did not proliferate in response to IFN-.gamma., whereas they proliferated in response to IL 2 or T cell clone supernatants. IFN-.gamma. did not stimulate nor inhibit the proliferative response of human B lymphocytes stimulated with optimal concentrations of anti-IgM antibodies or SAC. Additionally none of the different IFN-.gamma. tested had B cell differentiation factor activity in the standard SAC assay. These results indicate that IFN-.gamma. sensitizes B cells to suboptimal mitogenic concentrations of anti-IgM antibody.

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