Immunoglobulin IgG4 and autoimmune hepatitis.

Introduction: IgG4 disease has been characterised by lymphoplasmacytic inflammation, rich in IgG4 plasma cells, elevated serum IgG4 and clinical improvement with steroid therapy. There is limited information about IgG4 plasma cells in autoimmune hepatitis (AIH). Aim of this study was to determine IgG4 plasma cells in autoimmune hepatitis and its impact on clinical course and treatment outcome.

Material Methods: Liver biopsies from 40 patients with AIH before therapy were subjected to IgG4 immunostaining. Clinical history, liver function tests and response to immunosuppressive therapy were recorded. Patients were monitored for 4 weeks. Liver biopsy from 23 non AIH patients served as control. Depending on the presence of IgG4 plasma cells on immunohistochemistry, patients of autoimmune hepatitis were grouped into IgG4 positive (group A) and IgG4 negative (group B). Both groups were compared before and after immunosuppressive therapy for clinicopathological features.

Results: Tissue IgG4 plasma cells > 5 per high power field (hpf) were seen in 10/40 (25%) and > 10 per hpf in 4/40 (10%) cases of AIH. None of the cases from control group (non AIH) were positive for IgG4 plasma cells. Group A patients were significantly younger than group B. (p < 0.05). There were no differences in histological severity but liver enzymes, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly higher in group A than group B. Post treatment biochemical improvement was similar in both groups.

Conclusion: IgG4 positive AIH patients were younger with more abnormal liver enzymes. There was no difference in histology and response to treatment in both groups.