The value of three immune complex assays in the management of systemic lupus erythematosus: an assessment of immune complex levels, size and immunochemical properties in relation to disease activity and manifestations.

Sixteen patients with systemic lupus erythematosus, fourteen with renal involvement have been studied over a 30-month period. Circulating immune complex levels have been assayed by three techniques. The results of tests on 141 sequential sera suggest that the three assays detected overlapping populations of the range of complexes present. Immune complex levels are shown to be good markers of disease activity and certain immunochemical properties of the complexes emerged as better markers than others. Immune complex size is a more important determinant of disease manifestation than are overall immune complex levels. High doses of intravenous methyl prednisolone, which did not reduce overall complex levels, reduced levels of those complexes (molecular weight 600,000-900,000 Daltons) associated with renal involvement.