Effect of interferon-gamma on B lymphocytes of patients with systemic lupus erythematosus.

We studied the effect of interferon-gamma (IFN-gamma) on B cells in systemic lupus erythematosus (SLE). Low density B cells, which were fractionated on density gradients of Percoll, increased, and high density B cells decreased in number in SLE. Proliferative response of the high density B cells to interleukin 4 was reduced by IFN-gamma in normal controls, but not in SLE. IgG production of whole B cells induced by interleukin 2 or phytohemagglutinin induced T cell factors was enhanced by IFN-gamma in both normal controls and SLE in which activated B cells were thought to be increased in number. Therefore, IFN-gamma may be one of the factors which promote polyclonal B cell activation in SLE.