title: A micromethod for the analysis of cryoglobulins via laser nephelometry: evaluation and comparison to C1q binding activity in autoimmune diseases in pediatrics.
abstract: Quantitative determinations of cryoglobulins (IgG, IgA, IgM, and C3) were performed by a laser nephelometry microtechnique on 250 serum samples from a group of pediatric patients suspected of having immune complex-mediated disorders. Approximately 50% of these samples were cryoglobulin positive. Patients with cryoglobulins were examined as three separate groups: systemic lupus erythematosus, presumptive autoimmune disorders, and chronic bacterial or viral infections. Nearly all of these patients have mixed cryoglobulins. The relation of cryoglobulinemia with serum hypocomplementemia and renal involvement was examined in a group of systemic lupus erythematosus patients. High levels of cryoglobulins were found in patients with hypocomplementemia and anti-DNA antibodies without clinical evidence of nephritis. Highly significant correlations were oberved between C1q binding activity, presence of cryoglobulins, and serum hypocomplementemia in systemic lupus erythematosus patients. Only 60% of the cryoglobulin positive samples had immune complex demonstrable by C1q binding. Cryoglobulin analysis using the laser nephelometry microtechnique permits screening of pediatric patients for the presence of immune complex, permits detection of low levels of cryoglobulins, allows quantitative determination of the specific imunoglobulin classes in the precipitate, and requires only a very small amount of blood suitable for the pediatric population.
mesh_terms: D001327:Autoimmune Diseases / Q000276:immunology*; D001424:Bacterial Infections / Q000276:immunology; D002908:Chronic Disease; D003172:Complement C1 / Q000378:metabolism*; D003450:Cryoglobulins / Q000032:analysis*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D009391:Nephelometry and Turbidimetry / Q000379:methods; D014777:Virus Diseases / Q000276:immunology
chemical_list: D003172:Complement C1; D003450:Cryoglobulins