Different types of cytotoxic lymphocytes recovered from the lungs of patients with hypersensitivity pneumonitis

To better characterize the cytotoxic lymphocytes present in the lung of patients with hypersensitivity pneumonitis (HP), we studied cells recovered from bronchoalveolar lavage (BAL) of 5 subjects with farmer's lung disease. Specifically, this cytotoxic activity was evaluated: (1) in resting conditions and after boosting with interleukin-2 (IL-2) against NK-sensitive, NK-insensitive target cell lines, and against specific antigen-sensitized (Micropolyspora faeni) autologous monocytes; (2) after removal of NK-related populations; (3) in blocking experiments with CD3 and CD2 monoclonal antibodies. It has been demonstrated that lung lymphocytes from patients with HP in resting conditions are able to lyse both NK-susceptible and NK-resistant targets and that IL-2 is able to induce BAL cells to generate lymphokine-activated killer (LAK) cell activity. Neither resting nor activated HP lung lymphocytes were capable of specific lysis of autologous monocytes previously sensitized with specific antigen. Removal of HNK-1+ or CD16+ cells reduces, but does not completely eliminate the cytotoxic function, whereas blocking with anti-CD3 monoclonal antibody almost completely abolishes the cytotoxicity. All these data taken together suggest that different types of cytotoxic cells are recovered from the BAL of patients with HP, i.e., NK cells and non-MHC-restricted cytotoxic lymphocytes, including LAK cells.