Cryoglobulins. III. Further studies on the nature, incidence, clinical, diagnostic, prognostic, and immunopathologic significance of cryoproteins in renal disease.

Serial serum samples from a large number of patients with immunologic renal disease, normal healthy controls, acute infections as well as non-immunological renal disease were studied for the presence, nature and properties of cryoproteins, and these correlated with serial renal functional, morphologic, immunohistologic and clinical fingings as well as serologic observations. A high incidence of cryoproteins were found in renal disease thought to be mediated by immune complexes. Cryoprecipitates were not detected in the other patients. The presence of fibrinogen in a serum cryoprecipitate was always associated with rapidly progressive disease and poor prognosis. An association between the detection of cryoproteins and the clinical and morphological activity of disease was observed. Persistence of cryoproteinemia was associated with progression and apparent disappearance with resolution or progression to end stage renal disease. In patients with hematuria or proteinuria of questionable significance cryoprotein detection was always associated with immune complex nephritis. Renal transplantation in the presence of cryoproteinemia was associated with recurrent nephritis in the graft. Cryoproteins were found to have biologic properties attributable to antigen-antibody complexes, to contain immune complexes of antigen and antibody and to have serologic factors concentrated. The detection of serum cryoglobulins was found to be a better index of clinical and morphologic activity of immune complex renal disease than was serum complement. As in our previous studies, these proteins appear to be of diagnostic and prognostic value in renal disease and provide a method of antigen identification in these disorders.