Lysis of human alveolar macrophages by lymphokine-activated killer cells.

In order to determine if human LAK cells were cytotoxic against autologous AM phi, we studied the ability of human peripheral blood MNCs, stimulated in vitro with recombinant human IL-2, to lyse AM phi in a four-hour 51Cr-release assay. These cells showed significant cytotoxicity against autologous AM phi. The AM phi which had been cultured for four days served as better targets than freshly isolated AM phi. Kinetic study showed that the lysis of AM phi was proportional to the incubation time of MNCs with IL-2 and that LAK cells against AM phi required two days of in vitro culture with IL-2 for their induction. Freshly isolated MNCs did not lyse AM phi but did lyse K562 target cells, indicating that AM phi are natural killer-resistant. The phenotypes of effector cells against AM phi were found to be CD8+ or CD16+ (or both). These studies indicate that IL-2 can generate LAK cells against autologous AM phi, and this cytolytic activity must be taken into account when IL-2 or LAK cells are used for immunomodulation in patients with cancer.