Clinical evaluation of serum antimitochondrial antibody-negative primary biliary cirrhosis.

BACKGROUND

Primary biliary cirrhosis (PBC) is characterized by frequent presence of antimitochondrial antibodies (AMAs). The sensitivity and specificity of AMA for PBC are both greater than 90%-95%, so the presence of AMA in serum is the major hallmark in PBC. However, it has long been recognized that in 5%-10% of patients the clinical, biochemical and histological features are diagnostic for PBC, but their sera are consistently tested negative for AMA/AMA-M2. This study aimed to evaluate whether the presence of AMA alters the clinical, serological and histological features of the disease.

METHODS

Clinical data of 70 patients clinically and/or histologically diagnosed with PBC were reviewed. AMA-negative and AMA-positive patients were compared in terms of clinical, biochemical, immunological and histological features.

RESULTS

At presentation, 11 patients were serum AMA/AMA-M2 negative. At the initial visit, AMA-negative and AMA-positive patients were similar in terms of age, sex, clinical manifestations, liver biochemistries and histological findings. The mean level of serum immunoglobulin M (IgM) was significantly lower in AMA-negative PBC patients than in AMA-positive PBC patients (2851+/-1418 mg/L vs 6361+/-4928 mg/L, P=0.033). Serum antinuclear antibodies (ANA) and/or smooth muscle antibodies (SMA) were more frequently positive in the AMA-negative PBC patients than in the AMA-positive patients (81.8% vs 40.7%, P=0.031).

CONCLUSION

AMA-negative PBC patients are characterized by relatively lower levels of serum IgM and a higher prevalence of serum ANA/SMA and are not associated with substantial differences in the clinical biochemical and histological spectrum of the disease.