Cryoglobulinemia in systemic lupus erythematosus: Prevalence and clinical characteristics in a series of 122 patients

Objectives: To determine the prevalence and nature of cryoglobulins in 122 patients with systemic lupus erythematosus (SLE) and identify the clinical and immunologic features related to their presence. Methods: In a cross-sectional study, we investigated 122 consecutive patien ts (106 women and 16 men) with SLE who fulfilled the 1982 revised criteria of the American College of Rheumatology for the classification of SLE. All patients had documented medical histories and underwent a medical interview as well as a routine general physical examination by a qualified internist , and their clinical and serologic characteristics were collected on a prot ocol form. Serum samples were obtained at 37 degreesC, and cryoglobulinemia was estimated by centrifugation at 4 degreesC after incubation for 7 days in all patients. The type of cryoglobulinemia was identified by agarose gel electrophoresis and immunofixation. Results: Cryoglobulins were detected in the sera of 31 SLE patients (25%): 20 patients (65%) had a cryocrit lower than 1%, 8 (26%) had percentages ran ging between 1% and 5%, and only 3 patients (9%) had a cryocrit over 5%. On ly cutaneous vasculitis (39% v 16%; P = .01) was more prevalent in patients with than in those without cryoglobulins, Rheumatoid factor (RF) (42% v 15 %; P = .002) and low CH50 levels (84% v 49%; P < .001) were more prevalent in SLE patients with cryoglobulins. Hepatitis C virus (HCV) infection was i nvestigated in 24 of the 31 cryoglobulinemic SLE patients and was detected in 5 (21%). In comparison, 4 (5%) of the 75 noncryoglobulinemic SLE patient s studied were positive (P = 0.035; odds ratio, 4.67). Patients with a cryo crit greater than 1% showed a higher frequency of HCV infection than those with a cryocrit less than or equal to 1% (46% v 0%, P = .01). Conclusions: Cutaneous vasculitis, RF, hypocomplementemia, and HCV infectio n were associated with cryoglobulins in SLE patients. Testing for HCV infec tion is therefore recommended for patients with SLE and cryoglobulinemia to identify this subset of patients for prognostic and therapeutic reasons. Semin Arthritis Rheum 30:366-373. Copyright (C) 2001 by W.B. Saunders Compa ny.