It still remains unclear how antimitochondrial
autoantibodies (AMA) are involved with immunopathogenesis of
primary biliary cirrhosis (PBC). We have suggested the potential role of
IgA-AMA in damage to epithelial cells in PBC. In the current study, we investigated whether
IgA-AMA were detectable in sera and saliva of PBC patients, to examine the association between detectable
IgA-type
autoantibodies in sera or saliva and progression of
liver diseases. Fifty-three patients with PBC were enrolled, and
IgA-AMA in sera and saliva were sought by immunoblotting using pork heart mitochondria as
antigens. The progression of PBC was determined as Scheuer's classification consisting of four histological stages. We found
IgA-AMA, IgA-anti-PDC-E2, and IgA-anti-E3BP in 43/53 (81%), 37/53 (70%), and 35/53 (66%) sera of patients with PBC, but none of controls. The progression of PBC was statistically associated with presence of IgA-anti-PDC-E2 (P = 0.0124), but neither with
IgA-AMA (P = 0.1296) nor anti-IgA-E3BP (P = 0.5973). In saliva, detectable
IgA-AMA, IgA-anti-PDC-E2, and IgA-anti-E3BP were noted in 12/26 (46%), 6/26 (23%), and 11/26 (42%), respectively. Detection of IgA-anti-PDC-E2 was strongly associated with progression of PBC (P = 0.0002), whereas detection of
IgA-AMA and IgA-anti-E3BP were not associated (P = 0.2145 and P = 0.5118). The current findings suggest that the presence of IgA-anti-PDC-E2 in sera or saliva might be associated with progression of PBC, although a prospective study with PBC patients with detectable IgA-anti-PDC-E2 at early stages will be required to conclude the contribution of IgA-anti-PDC-E2 to the progression of PBC.