Objective: The proportion of cell proliferation-associated nuclear Ki-67 antigen positive alveolar macrophages was compared in the bronchoalveolar lavage fluids (BAL) of patients with dermato-/polymyositis (DM-PM), scleroderma-myositis overlap syndrome (Scl-M), systemic sclerosis (SSc), and undifferentiated connective tissue disease (UCTD).
Patients and methods: We examined 8 patients with DM-PM, 3 with Scl-M, 11 with SSc, and 10 with UCTD. The patients were selected on the basis of their interstitial lung involvement diagnosed by non-invasive methods.
Results: Increased Ki-67 expression in alveolar macrophages was observed in three cases of SSc (27%) and in 4 of myositis (36%). In UCTD and in healthy volunteers a low level of Ki-67 expression was detected (in both groups 5%). A positive correlation was found between the percentage of the Ki-67 positive alveolar macrophages and the percentage of granulocytes in BAL fluid of the investigated patients with different systemic autoimmune diseases and healthy controls, indicating that increased local proliferation of differentiated large alveolar macrophages can be detected in cases with neutrophil alveolitis. There was also a correlation between the extent of ground glass opacity on HRCT and elevated proportion of proliferating alveolar macrophages in BAL fluid.