Soluble intercellular adhesion molecule-1 as an early detection marker for radiation pneumonitis

To investigate the role of intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of radiation pneumonitis and to determine whether the measurement of soluble ICAM-1 (sICAM-1) levels is useful for predicting the onset of pneumonitis, the levels of sICAM-1 were measured in serum and bronchoalveolar lavage (BAL) fluids from patients with lung malignancy who received radiotherapy. A total of 30 patients were irradiated with a total dose of approximately 60 Gy. Blood samples were taken before, midway and after radiotherapy. BAL was also performed before and after radiotherapy in seven cases. The sICAM-1 concentration was measured using an enzyme-linked immunosorbent assay kit with two different monoclonal antibodies. Twelve out of 30 cases developed radiation pneumonitis (pneumonitis group), and the other cases did not (nonpneumonitis group). Serum levels of sICAM-1 after radiotherapy were significantly elevated in the pneumonitis group, but not in the nonpneumonitis group. In some of the cases in the pneumonitis group, sICAM-1 levels began to increase at an early phase of irradiation. In one case of pneumonitis in which BAL was performed, the total cell count and the number of lymphocytes increased markedly, as did the level of sICAM-1 in BAL fluid. These findings suggest that intercellular adhesion molecule-1 may play an important role in the development of radiation pneumonitis and that soluble intercellular adhesion molecule-1 may be a useful marker for the early detection of radiation pneumonitis.