Immunologic events preceding clinical exacerbation of systemic lupus erythematosus

A patient with diffuse glomerulonephritis due to systemic lupus erythematosus is described. Serial urinalyses and special immunologic determinations were performed as he responded to treatment of his first attack of systemic lupus erythematosus. The sequence of immunologic events preceding the onset of his second attack of lupus nephritis are recorded. Falling levels of total serum complement (CH₅₀) and of the first component of complement (C1q), rising levels of antibody to double and single stranded deoxyribonucleic acid (DNA) and finally circulating protein complexes that precipitate C1q in vitro developed months before clinical evidence of exacerbation of his extra renal or renal disease. Abnormalities of L-chain protein metabolism provided a particularly early guide to exacerbation of the disease. The use of this group of laboratory determinations to anticipate exacerbations of the disease and to guide therapy is discussed.