title: Human interferon-gamma acts as a B cell growth factor in the anti-IgM antibody co-stimulatory assay but has no direct B cell differentiation activity.
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.
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D007371:Interferon-gamma / Q000494:pharmacology*; D015847:Interleukin-4; D008222:Lymphokines / Q000494:pharmacology*; D014066:Palatine Tonsil / Q000166:cytology; D011994:Recombinant Proteins / Q000494:pharmacology; D013154:Spleen / Q000166:cytology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D006133:Growth Substances; D007075:Immunoglobulin M; D008222:Lymphokines; D011994:Recombinant Proteins; C044203:anti-IgM; D015847:Interleukin-4; D007371:Interferon-gamma