Serum immune complexes and disease activity in lupus nephritis.

Raised levels of circulating soluble immune complexes were found in sera of 21 of 29 patients with lupus nephritis. They correlated well with clinical disease activity in the group as a whole and with the course of individual patients. In 2 patients, high-dose methylprednisolone reduced levels of immune complexes and led to clinical improvement. The size of the IgG complexes was studied in 7 patients. The complexes were very large (2-5-4X10(6) M.W.) in 6, but only the 4 with diffuse proliferative glomerulonephritis had medium-sized IgG complexes (1-1-5X10(6) M.W.) as well.