CHE and Alk induce apoptosis in human PMNs by a H
-dependent mechanism. PMNs were isolated and incubated (10 × 106 cells/mL) with buffer, CHE (500 μg/mL) or Alk (100 μg/mL) in the presence (+) or absence (−) of catalase (CAT) for 24 h. Apoptosis was evaluated by cytology as described in Methods. Results are means ± SEM (n ≥ 3). *, p < 0.05 vs Ctrl (CHE, Alk and CAT), #, p < 0.05 vs CHE or Alk (as indicated) by Student’s t-test.