Immunopathology of early and clinically silent lupus nephropathy.

Detailed immunopathologic studies of early or silent renal alterations in systemic lupus erythematosus have been sparse. The renal biopsies of 16 lupus patients with normal renal function, including 8 with hematuria and/or proteinuria of recent onset, and 8 without clinically detectable renal disease were investigated by light, immunofluorescence, and electron microscopy. Immunoglobulins, complement components, and electron-dense deposits were detected in glomeruli of all patients, regardless of morphologic appearance or lack of clinical evidence of renal involvement. Features of membranous glomerulonepritis were observed in 4 patients with substantial proteinuria. In the remaining 12 patients, including 3 with hematuria and 4 with slight proteinuria, either minimal glomerular alterations or features of mesangial proliferative glomerulonephritis were seen. Transformation of the original disease was demonstrated in 3 of 3 patients rebiopsied within 2 years. The significance of these findings is discussed in relation to a) the spectrum of clinical and immunopathologic alterations in lupus nephritis and b) transformation of the original disease.