Cryoglobulins. I. Studies on the nature, incidence, and clinical significance of serum cryoproteins in glomerulonephritis.

Abstract Cryoglobulins were isolated from the sera of 14 of 18 patients with acute poststreptococcal glomerulonephritis, 4 of 4 with nonstreptococcal proliferative glomerulonephritis, and 2 of 3 with membranous nephropathy. They were not detected in patients with end-stage renal disease lipoid nephrosis, acute streptococcal pharyngitis, rheumatic fever, and normal persons. Cryoglobulins contained IgG and β 1C , and in 3 patients IgM was also present. Their presence was associated with activity of renal disease. A relationship between persistence and progression and disappearance and improvement was suggested. There was no correlation between the presence or quantity of cryoglobulins and levels of immunoglobulins or complement in the serum. Antistreptococcal or rheumatoid factor activity could not be demonstrated in any of the cryoprecipitates. IgG, β 1C , and occasionally IgM were localized in the renal glomeruli by immunofluorescence. The identification of these same proteins in the cryoglobulins of these patients suggests that cryoprecipitates may be of immunopathologic significance in immune complex nephritis.