ObjectiveTo understand the clinical significance of interleukin12(IL12) in pulmonary tuberculosis (TB).MethodsSerum IL12 in 80 TB patients before receiving antiTB treatment were detected by enzymelinked immunosorbent assay, and were compared with 30 healthy volunteers (healthy control) and 20 patients with 6month followup after effective antiTB treatment, significance of IL12 was studied in patients who were subdivided into several groups according to common clinical indicators of TB.ResultsThe average serum IL12 level in 80 pulmomary TB patients was (41.49±34.22)pg/mL, which was significantly lower than (58.12±44.92)pg/mL in healthy control group(t=2.51,P<0.05). Serum IL12 level in 20 followedup patients increased from (12.93±12.48)pg/mL before treatment to (66.26±20.97)pg/mL after treatment (t=-6.88,P<0.05). There was no significant difference in serum IL12 level between 20 followedup patients and healthy control group(t=-0.60,P>0.05).There was no statistical difference in serum IL12 level between the following groups respectively: simple pulmonary TB/pulmonary TB associated with tuberculous pleurisy, pulmonary cavity/nonpulmonary cavity, lung lesions showed by CT <3 lobes/≥ 3 lobes, sputum TB positive/negative, tuberculin test positive/negative, elevated erythrocyte sedimentation rate (ESR)/ normal ESR, PPD strongly positive/ nonstrongly positive (all P>0.05).ConclusionIL12 level is closely related with activity in pulmonary TB, it can reflect the immune state in patients, and judge activity and prognosis of pulmonary TB.