Previous studies have not clearly defined the role of cell-mediated immunity
in bleomycin-induced
lung injury. In this report the functional activity of T lymphocytes obtained from minced lung preparations, bronchoalveolar lavage, and blood of rabbits treated with
bleomycin was examined in cell proliferation and cell-mediated cytotoxicity assays. Four days after instillation of
bleomycin (10 units/kg) into the right lung, histologic examination revealed mononuclear cell interstitial infiltrates and alveolar exudates. Right lung bronchoalveolar lavage (BAL) cell counts were similar in both groups, but the percentage of lymphocytes and neutrophils was elevated
in bleomycin-treated groups (25% vs. 7% and 35% vs. 0% respectively; p less than 0.05). Spontaneous proliferation of cultured BAL and blood lymphocytes was similar
in bleomycin-treated rabbits and controls. After 24 h of incubation with
interleukin-2 (IL-2), BAL lymphocytes from
bleomycin-treated rabbits had nearly a 4-fold greater proliferative response than lymphocytes from untreated rabbits.
Concanavalin-A-dependent cell-mediated cytotoxicity (CDCMC) assays were performed to evaluate cytolytic lymphocyte activity. Spontaneous CDCMC activity was not detected in BAL fluid or in blood lymphocytes from either treated or control animals. After 24 h of incubation with
IL-2, significant CDCMC activity was detected in lung lymphocytes from
bleomycin-treated animals, but not in lung lymphocytes from control animals. These results indicate that stimulated lymphocytes are present in the lungs of rabbits 4 days after exposure to
bleomycin.