Long term administration of cyclophosphamide into MRL/1 mice. II. The effects on the isotype of anti-DNA antibodies and immunoglobulin secreting cells in the spleen.

Weekly injections of cyclophosphamide (Cy) at a dose of 20 mg/kg body weight prevented IgM to IgG class switch of serum anti-DNA antibodies and also immunoglobulin secreting cells in the spleen of MRL/Mp-lpr/lpr (MRL/1) mice. Culture experiments revealed that splenic B cells of Cy treated mice gave rise to more IgM and less IgG secreting cells than those of untreated mice in response to lipopolysaccharide. These results suggested that Cy suppressed enhanced differentiation of B cells into IgG secreting cells in MRL/1 mice, which would result in reduction of IgG anti-single stranded DNA antibodies and improvement of murine lupus like syndrome.