OBJECTIVETo investigate the serum myeloperoxidase (MPO) activity and serum paraoxonase-1 (PON-1) activity in patients with silicosis and observation subjects and their clinical significance.

METHODSSeventy-two patients with silicosis (stage I: 30 cases, stage II: 22 cases, stage III: 20 cases) and 37 observation subjects were selected as a case group, and 110 healthy men were selected as a control group. Serum MPO activity was measured by double-antibody sandwich enzyme-linked immunosorbent assay, and serum PON-1 activity was measured by chemical spectrophotometry.

RESULTSSerum MPO activity was significantly higher in the case group than in the control group [(102.1 ± 15.7) U/L vs. (62.4 ± 11.4) U/L, P < 0.01], but serum PON-1 activity was significantly lower in the case group than in the control group [(85.4 ± 15.7) U/ml vs. (125.4 ± 13.7) U/ml, P < 0.01]. Serum MPO activity was significantly lower in patients with stages I, II, and III silicosis than in the observation subjects [(91.3 ± 13.5) U/L, (85.7 ± 14.4) U/L, and (88.6 ± 14.5) U/L vs. (128.4 ± 16.4) U/L, P < 0.01]. Serum PON-1 activity declined as the stage of silicosis increased; serum PON-1 activity was significantly lower in the patients with stages II and III silicosis than in the observation subjects and the patients with stage I silicosis [(70.4 ± 11.4) U/ml and (67.6 ± 13.7) U/ml vs. (101.5 ± 14.0) U/ml and (89.1 ± 10.1) U/ml, P < 0.01].

CONCLUSIONSerum MPO activity and serum PON-1 activity are valuable for early diagnosis of silicosis and evaluation of patient's condition.