Abstract
In vitro spontaneous synthesis of immunoglobulins and anti-single-stranded DNA antibodies (anti-ssDNA) by mononuclear cells (MNC) and monocyte-depleted MNC was examined in patients with systemic lupus erythematosus (SLE) and compared with that in normal individuals. MNC were isolated by Ficoll-Hypaque density gradient centrifugation. Monocytes were depleted by treatment with thrombin. MNC were cultured for 7 days. The culture supernatants were measured for IgG and IgM by enzyme-linked immunosorbent assay and for anti-ssDNA by solid phase redioimmunoassay, respectively. In SLE, significantly increased synthesis of immunoglobulins by MNC was reduced when monocytes were depleted. In the normal individuals, depletion of monocytes tended to increase synthesis of IgG and IgM. SLE monocytes seemed to play a helper role in synthesis of IgG and IgM by MNC, while normal monocytes seemed to play a supperssor role. Levels of anti-ssDNA of either IgG or IgM class in the culture supernatant correlated well with those in sera obtained at the time when MNC were examined. These findings indicating preference that studies on in vitro synthesis of specific autibodies are useful in elucidating the mechanism of autoantibody production in vivo.
