Lupus Erythematosus: Comparison of Functional Activities vs Protein Concentrations of C3 and C4, Antinuclear Antibody Levels, and Skin Immunofluorescence

Abstract

Lupus erythematosus (LE) is an immunemediated disease which may feature profound degenerative and inflammatory reactions. Sera and biopsy specimens from patients with LE were tested in four different assays. Serum C3 and C4 levels were measured by functional hemolytic titrations and by quantification in radial immunodiffusion plates by using antisera to β1C/β1A and C4 (β1E). Antinuclear antibody (ANA) levels were determined by an indirect immunofluorescent method with mouse fibroblast cells and conjugated anti-IgG (kappa and lambda) antiserum. Skin immunofluorescence (SI) was determined with biopsy material from involved and uninvolved skin areas, with conjugated monospecific anti-IgG, IgM, IgA, and β1C/β1A antisera. The results showed a significant number of patients with normal C3 and C4 protein values, but decreased functional hemolytic titers (28%). A smaller group of patients had depressed C3 and C4 protein values but normal functional hemolytic activities.