Autoimmune hepatitis type 1 (AIH1) is an autoimmune disease attacks the liver and characterized by periportal inflammation, elevated immunoglobulins, and autoantibodies. The central role of B lymphocyte in pathogenicity of AIH1 is unclear. Here, the effect of antibody-secreting cells activity in terms of number of plaque-forming cells (PFC) on severity of AIH1 was evaluated. The high number of PFC-(IgG and IgM) in peripheral blood of patients with AIH1 was observed and this was concomitant with increase in the number of CD4+ T lymphocyte, immunoglobulin (Ig) (IgG and IgM) concentrations, and levels of liver function tests (LFTs). However, the negative correlation (r +0.5, P < 0.05). The high expression of IL-10 mRNA was found in the tissue culture of peripheral blood lymphocytes obtained from patients with AIH1 as compared with that isolated from control group (P < 0.05). The current study proved the direct role of (IgG and IgM)-secreting cells in severity of AIH1. This was associated with CD4+ cell numbers and IL-10 mRNA expression, and mediated by IgG and IgM.