Objective: To evaluate the clinical features of patients with primary biliary cirrhosis (PBC) and positive expression of sp100 autoantibody in order to generate a clinical screening profile that may help to increase early diagnosis and timely initiation of therapy.
Methods: The clinical data of 70 patients who were diagnosed with PBC by liver biopsy between January 2006 to December 2009 at the Second Affiliated Hospital of Kunming Medical University of Hepatobiliary and Pancreatic Medicine were retrospectively collected for analysis. The patients were divided according to expression of anti-sp100: positive patients, n = 12; negative patients, n = 58. The groups were comparatively analyzed for differences in clinical, biochemical, immunological, and histopathological parameters. Normally distributed data was compared by t-test, and non-normally data was compared by rank-sum test.
Results: There was no significant difference in age among the sp100-positive and sp100-negative patients (51.6 +/- 9.5 vs. 50.0 +/- 14.7 years, P more than 0.05). The sp100-positive group had significantly more women (80.0% vs. 61.9%, X2 = 0.32, P more than 0.05) and more patients with atypical symptoms (18.2% vs. 13.8%) but the difference of the latter did not reach statistical significance. The sp100-positive group had significantly higher levels of alkaline phosphatase (ALP; 466 vs. 163 U/L, Z = 3.71), gamma-glutamyl-transpeptidase (GGT; 728 vs. 154 U/L, Z = 3.38), and immunoglobulin M (IgM; 4.25 +/- 2.86 vs. 2.81 +/- 2.15, t = 2.06, P less than 0.05). Forty of the total patients tested negative for antimitochondrial (AMA)-M2 antibodies, and eight of those were sp100-positive (20.0%) while 18 were antinuclear (ANA) antibody-positive (45.0%). There were significantly more AMA-M2-negative/ANA-positive patients than sp100-positive patients (P = 0.021). Anti-sp100 expression was not associated with the pathological stage of PBC (R1 = 5.500, P more than 0.05).
Conclusion: SP100-positive PBC may show a bias towards the female sex, and may be characterized by enhanced serum levels of ALP, GGT, and IgM. Further clinical differences may manifest as the disease progresses, and changes in autoantibodies' expression and liver function markers should be carefully monitored in follow-up.