This is a pilot, open-label, study on 10 female patients with AMA-positive PBC to determine the effects of two infusions of rituximab on response of memory B cells to bacterial motifs, on biochemical function, and histological features. We will enroll 10 consecutive AMA-positive patients with the diagnosis of PBC based on internationally accepted criteria and histological staging determined at liver biopsy and being currently treated with UDCA. Importantly, patients with advanced histological stages, decompensated liver disease, or waiting for OLT will not be included in the study (see exclusion criteria).