Production of the autoantibodies in patients with chronic hepatitis C virus infection

by Margarida, Patricia Estevam

Introduction: Viral hepatitis C (HVC) is a serious public health problem in Brazil. An important aspect of the VHC immunology is the production of autoantibodies and cryoglobulins. However such immune aspect of VHC has not been studied in Brazilian patients.Purpose: To investigate the frequency of the autoantibodies of Brazilian hepatitis C virus carriers.Experimental design: The target group was represented by 60 VHC patients (median age = 47 years; 36 male and 24 female), while 40 healthy blood donors (HI) were included as controls. The following autoantibodies (Ab) were investigated by ELISA (INNOVA Diagnostics, Inc., USA): antinuclear IgG (ANA), anti-extractable nuclear antigens SSA, SSB, Sm and RNP, anti-dsDNA, anticardiolipin antibodies (ACA) of the IgA, IgG and IgM isotypes, anti-cyclic citrullinated peptide (anti-CCP2) and anti-LKM1. Anti-smooth muscle antibody (SMA) was evaluated by an indirect fluorescent antibody test from this same source. Antibodies to thyroid peroxidase (TPO-Ab) and anti-thyroglobulin (Tg-Ab) were investigated by indirect agglutination (Fujirebio, Inc., Japan), while IgM rheumatoid factor (RF-IgM) was tested by turbidimetry (BioSystems S.A, Spain). Cryoglobulins were investigated by tube and gel cryoprecipitation.Results: Thirty-nine out of 60 (65%) patients had cryoglobulinemia. ANA was detected in 30% VHC patients (15 male and 6 female) and 15% HI controls. Only ENA-SSA was recognized by these ANA positive VHC patients (10%) that were seronegative for anti-dsDNA Ab. All HI controls were seronegative for these nuclear antigens. IgG and IgM ACA (> 20 PL U/ml) was found in 3% and 35% VHC patients respectively, but VHC group was negative for IgA-ACA. IgM-RF (cutoff = 31 IU/ml) was observed in 45% VHC patients and 13.3% HI controls, while only one of these VHC patients had CCP-Ab. SMA (titer ? 40) was observed in 30% VHC patients, only one (1.7%) had anti-LKM1 autoantibodies, and 7% of them had anti-TPO and/or anti-thyroglobulin (titer > 100). Clinical signs of autoimmunity were rarely found in VHC patients.Conclusions: The findings show that cryoglobulinemia and autoantibody production are important immunological aspects of the immune response of VHC in Brazilian patients. However, such findings are not associated with clinical signs of autoimmune diseases