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Suppressive Effect of Interferon‐β‐Activated Natural Killer Cells on Lipopolysaccharide‐Induced B Cell Differentiation of MRL/Mp‐1pr/1pr Mice

The suppressive effects of mouse recombinant interferon‐β (IFN‐β) on B cell differentiation of MRL/Mp‐1pr/1pr (MRL/1) mouse, a model of autoimmune diseases, and C3H/H2 mice, a normal situation, were investigated. Spleen mononuclear cells were cultured in the presence of lipopolysaccharide (LPS), and the suppressive effect of IFN‐β was examined on differentiation of B cells to plaque‐forming cells (PFCs) by highly sensitive reversed hemolytic plaque assay. IFN‐β (5,000–10,000 units/ml) suppressed more than 50% of PFCs of both MRL/1 and C3H/H2 mice. This suppressive activity as well as the cytotoxicity of natural killer (NK) cells enhanced by IFN‐β was abrogated by treatment of the spleen cells with anti‐asialo GM1 antibody in the presence of complement. This suppressive activity was also abrogated by intravenous administration of 20 μl/mouse of anti‐asialo GM1 12 hr before cultivation of spleen cells. These results suggest that NK cells activated by IFN might be responsible for the immunoregulation in autoimmune diseases.