Serum cryoglobulins and disease activity in systematic lupus erythematosus

Background: To determine the prevalence of cryoglobulins in Iranian patients with systemic lupus erythematosus (SLE) and evaluate the correlation of cryoglobulins with disease activity in these patients. Materials and Methods: In a cross-sectional study, we investigated 80 consecutive women who fulfilled the 1982 revised criteria of the American College of Rheumatology for the classification of SLE. All the patients had undergone a medical interview and general physical examination by a rheumatologist for clinical and serologic characteristics of SLE. For the determination of cryoglobulins, sera were collected by a standard protocol at 37°C, and after incubation at 4°C for seven days, the level of cryoglobulins was estimated for each patient. Results: Cryoglobulins were detected in the sera of 39 (48.8%) patients. All of these patients had cryocrit over 5%. Disease was active in 30 patients [SLEDAI ≥6 (DAI: disease activity index)] and inactive in 50 (SLEDAI