Patients having autoimmune chronic diseases may develop anti-C1q- autoantibodies.

Anti-C1q-autoantibodies were determined in sera from 42 SLE-patients treated at the Belarus Rheumatology Center. All diagnoses were confirmed according to American Rheumatology Association criteria. The majority of patients were female (95.2%). Clinical characteristics of patients: 4 (9%) had mild disease, 25 (60%) – moderate disease, and 13 (31%) – severe disease. The control group included 10 healthy adults. The concentration of anti-C1q- autoantibodies was determined by an ELISA method.

The level of anti-C1q- autoantibodies in SLE patients (118.16 ± 24.88 U/ml) was significantly greater (p<0.05) than in the control group (4.9 ± 1.95 U/ml). There was a significant correlation between disease activity and serum anti-C1q- autoantibody levels. The greatest anti-C1q- autoantibody titers were found in SLE patients with severe disease (215.67 ± 45.42 U/ml), while in patients with moderate and low disease anti-C1q- autoantibody levels were 82.13 ± 30.36 U/ml and 26.5 ± 12.01 U/ml respectively. There was also positive correlation between anti-C1q- autoantibody levels and antibodies to DNA (r=0.36).

The evaluation of anti-C1q- autoantibody concentrations may assist in assessment of the disease severity of SLE patients.