Accessory function and costimulatory molecule expression of alveolar macrophages in patients with pulmonary tuberculosis

An effective immune response against M. tuberculosis requires a coordinated interaction of alveolar macrophages (AM) and lymphocytes. Secondary signal s, such as accessory function (AF) of antigen presenting cells and interact ion of costimulatory molecules are also important for T cell activation. In the present study we determined the AF and the expression of CD11a, CD54, CD58, CD80, CD86 and HLA-DR costimulatory molecules by AMs lavaged from pat ients with pulmonary tuberculosis and controls. We hypothesized that altera tions in AF and costimulatory molecule expression may influence the present ation of tuberculosis. Therefore these parameters were also correlated with the radiographic extension of the disease. AMs of patients with tuberculos is exhibited an increased AF and a significantly increased expression of co stimulatory molecules compared with controls. Furthermore, we observed that the expression of CD54 (ICAM-1) decreased with the course of the disease. We conclude that the infection by M. tuberculosis results in an increased A F of AMs and the acitivity of AMs remains uninfluenced by the extension of the disease. Clear-cut changes of patterns of costimulatory molecule expres sion by AMs could not be observed with the progression of tuberculosis.