Rigopoulou EI, Davies ET, Bogdanos DP, Liaskos C, Mytilinaiou M, Koukoulis GK, Dalekos GN, Vergani D. Antimitochondrial antibodies of immunoglobulin G3 subclass are associated with a more severe disease course in primary biliary cirrhosis.
Liver Int 2007;
27:1226-31. [PMID:
17919234 DOI:
10.1111/j.1478-3231.2007.01586.x]
[Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND/AIMS
Primary biliary cirrhosis (PBC) is characterised by the presence of immunoglobulin (Ig) G antimitochondrial antibodies (AMA), which are routinely detected by indirect immunofluorescence (IFL) using composite rodent tissue substrate. The IgG subclass distribution and clinical significance of IFL-detected AMA in patients with PBC have not been previously studied in detail.
METHODS
We have examined IgG subclass-specific AMA detected by IFL on rodent liver, kidney and stomach tissue substrate using affinity-purified IgG subclass monospecific antisera as revealing reagents in 95 AMA-positive PBC patients from Greece.
RESULTS
AMA of any of the IgG1, IgG2 or IgG3 subclasses were present in 89/95 (93.7%) patients. Among those 89, 55 (61.8%) had IgG1, 2, 3 AMA positivity; eight (9%) had IgG1, 2; seven (7.9%) had IgG2, 3; eight (9%) had IgG1, 3; nine (10.1%) had IgG1 subclass and two (2.2%) single IgG3 AMA reactivity. IgG4 AMA was absent. IgG3 titres were higher than IgG2 and IgG1 (P<0.001) and IgG1 higher than IgG2 (P<0.001). IgG3 AMA-positive patients had a histologically more advanced disease (P<0.01) and were more frequently cirrhotic compared with those who were negative (P<0.01). There was a positive correlation between AMA IgG3 titre and Mayo risk score (r=0.55, P=0.009, Spearman's correlation).
CONCLUSIONS
Our findings suggest that AMA are not restricted to a specific IgG subclass. AMA of the IgG3 subclass are associated with a more severe disease course, possibly reflecting the peculiar ability of this isotype to engage mediators of damage.
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