ROLE OF T-LYMPHOCYTES IN THE RESOLUTION OF ENDOTOXIN-INDUCED LUNG INJURY

An acute neutrophilic lung injury was compared in Balb/c normal and nu /nu (nude) mice to assess the role of T lymphocytes in the resolution of acute pulmonary neutrophilic inflammation following the administrat ion of endotoxin. Maximal neutrophilic infiltration occurred on day 1 post-endotoxin treatment and declined to near normal levels by day 5. In contrast, the percentage of lymphocytes in the bronchoalveolar lava ge (BAL) fluid increased from 1.8% an day 1 post-endotoxin to greater than 11% on days three and five, during which time neutrophil resoluti on was occurring. On days 1-5 after endotoxin administration, approxim ately 40% of the CD4 lymphocytes expressed the cell surface activation marker, CD69. Despite being CD69(+), CD4 cells did not express the hi gh affinity IL-2 receptor chain, CD25, to any significant extent on an y of the days studied. To assess the contribution of T cells to the ra te of clearance of neutrophils from the BAL, normal and nude Balb/c mi ce were compared for the percentage of neutrophils following nasal adm inistration of endotoxin. Endotoxin-treated nude mice did not demonstr ate significant differences in either the total white blood cell count s or in the clearance of neutrophils from the BAL, as compared to norm al Balb/c mice. These data indicate that the influx of activated T cel ls during the resolution of neutrophilic pneumonitis does not contribu te to the rate of neutrophil clearance during acute lung injury.