Immunofluorescent localization of immunoglobulins, complement, and fibrinogen in human diseases. I. Systemic lupus erythematosus.

Abstract

The fluorescent antibody technique was employed to study the localization of the following proteins in tissue lesions of 16 patients with systemic lupus erythematosus (SLE) : immunoglobulins (gamma2-, gammalM-, and gammalA globulins),beta1C-globulin (complement), fibrinogen and other plasma proteins (alpha2-macroglobulin and albumin). Gamma2 and gammalM immunoglobulin, complement and fibrinogen were localized in renal glomeruli and vessels of kidney, spleen, heart and liver, Alpha-2 macroglobulin albumin and gamma1A-globulin were absent from renal glomeruli, but the latter was visualized in tubular epithelium. Gamma1M- and gamma2 globulins were eluted by acid buffers. Nuclear localization of all immunoglobulins was seen in the renal tubular epithelium in only 3 of the 16 cases investigated. Histochemical staining for fibrin demonstrated hyaline thrombi and occasional glomerular deposit of fibrin, but failed to detect the diffuse pattern of glomerular fibrin deposition noted by the fluorescent antibody technique. The present study suggests that antibody in the gamma2- and gammalM-globulin fractions are component of complement fixing cytotoxic antigen-antibody complexes responsible for the renal and vascular lesions in SLE. The localization of fibrinogen in the renal glomeruli and vessels may result from anindependent alteration of the coagulation system, or it may be secondary to vascular injury. Fibrinogen deposition may contribute to renal damage,.