Type C RNA virus-specific antibody in human systemic lupus erythematosus demonstrated by enzymoimmunoassay

Abstract

Postmortem study of proliferative glomerulonephritis associated with human systemic lumpus has previously shown that an antigen related to mammalian type C RNA viral core (p30) proteins is deposited in the renal glomerular lesions with human immunoglobulins in an immune-complex pattern. In the present work, human immunoglobulins were sequentially eluted from the lupus glomerular immune deposits and were assayed by a sensitive enzymoimmunoassay developed for the measurement of anti-p30 antibody activity against purified viral p30 proteins of mammalian type C viruses. Human immunoglobulins showing specific anti-p30 antibody activity, particularly against p30 antigen of feline endogenous virus RD-114 and to a smaller extent against p30 antigen of murine type C virus, were eluted by acid buffer from the glomerular immune deposits in two patients with lupus proliferative glomerulonephritis who have deposits of viral p30-related antigen in the same tissue lesions. This study adds support for the hypothesis that expression of type C viral antigen may be involved in the multifactorial pathogenesis of proliferative glomerulonephritis associated with human systemic lupus.