Local esperience on frequency and significance of immunological overlap in the field of primary biliary cirrhosis (PBC)

The aim of this study was to investigate the frequency and quality of immunological overlap in serum AMA M2 positives. During the period January 2004 - December 2006, out of 3000 sera evaluated, 40 were AMA M2 positive. Six of these (15%) were without immunological overlap; they had clinical, histological and biochemical features of classical PBC with a normal length of life and ursodeoxycholic acid responding. In other 16 patients (40%), there was an association with antibody against antigens as SLA/LP, gp210 and Sp100, that causes the overlap syndrome AIH/PBC with various level of seriousness.The association with anti SLA/LP or with high level of autoantibody anti-Sp100 (index ELISA>10) waspresent in the patients investigated, as AIH type I°. Patients positive for anti gp210 with low anti-Sp100 index had instead a weak overlap AIH/PBC with slow evolving aspects. Nobody was positive for anti-LKM1, anti-LC, PML, or LBR.The remaining 45% of sera were positive for ANA, ENA,ANCA, with different clinical features. The antibody anti-SSARo52 and anti-centromere were frequent (17%) and modified the liver disease evolution.The most serious clinical case was a double overlap anti-centromere/SSARo52 with biochemical and histological AIH symptoms. Other ENA patterns did worsen the prognosis of PBC but showed or were associated with systemic diseases, often after a long asymptomatic period.The ANA IFI positive with a speckled pattern ENA negative, in other 7 patients (17%) worsened the long term prognosis because they expressed an overlap AIH/PBC with slowly evolving aspects.The most serious and intense clinical picture, with transplant perspective, was the association of the AMA M2 with anti Sp100 (index > 10) and pANNA. Four case were male (10%) but females were prevalent.