Bone marrow findings in patients with autoimmune liver diseases

We have recently reported quantitative and qualitative differences of the bone marrow (BM) hematopoietic progenitor cells in autoimmune hepatitis type-1 (AIH-1) and primary biliary cirrhosis (PBC). In order to better investigate the possible involvement of BM in these diseases, we studied the morphological abnormalities of BM aspirates in the same patients with AIH-1 and PBC.

BM smears from 13 AIH-1 and 13 PBC patients were investigated. BM from 12 patients with cirrhosis of non-autoimmune etiology and eight healthy individuals served as pathological (PC) and healthy controls (HC).

Erythroid, granulocyte and platelet precursors were variably altered. Polychromatic normoblasts and immature megakayocytes were higher in AIH-1 (11.9 +/- 2.9 and 16.2 +/- 16.9, respectively) and PBC (10.2 +/- 3.6 and 17.3 +/- 20.2, respectively) compared to PC (7 +/- 2 and 2.3 +/- 6.0, respectively) and HC (7.9 +/- 1.6 and 0 +/- 0, respectively) (P = 0.0001 and P = 0.006). In AIH-1, immature megakaryocytes were significantly higher in patients receiving immunosuppression (25.71 +/- 17.66 vs 5.00 +/- 5.48; P < 0.02) and were associated negatively with laboratory markers of disease activity. BM plasmacytosis was observed more frequently in AIH-1 compared to PBC and PC. BM monocytosis was found in all patients with AIH-1, PBC and PC whereas approximately half of the patients with autoimmune liver diseases and all PC had BM lymphocytosis.

BM monocytosis and lymphocytosis are commonly found in AIH-1 and PBC patients irrespective of the presence of cirrhosis or the use of immunosuppression. BM plasmacytosis appears to be a distinct finding in some AIH-1 patients, as similar findings were observed in only one PBC and one PC, whereas BM immature megakaryocytes characterize both AIH-1 and PBC. Whether BM is a target organ in AIH-1 and PBC needs further investigation.