Abstract: ObjectiveTo study the in fluence of baicalin(Bai)on tumournecrosis factor-α(TNF-α)and interleukin-8 (IL-8)on Pneumo cystis carinii pneumonia(PCP)in rats.MethodsSprague-Dawley(SD)rats were subcutaneo usly injected with dexamethasone sodium phosphate.The treatment group was treated by baicalin(Bai)before and after the PCP model established.The pathological change in lung tissue and the level of TNF-and IL-8 in sera were observed.ResultsThe contents of TNF-α of Bai treatment group(2.14±0.14 ng/mL),low dose group(2.57±0.15 ng/mL),moderate dose group(1.46±0.14 ng/mL)and high dose group(1.12±0.13 ng/mL)were higher than those of normal control group (0.70±0.21 ng/mL,P<0.05,P<0.01)and were lower than those of model control group(3.65±0.73 ng/mL, P<0.01).The contents of TNF-of SMZ/TM Pcontrol group(1.59±0.14 pg/mL)were higher than those of normal control group(P<0.01)and were lower than those of model control group(P<0.01).The contents of IL-8 of Bai treatment group(0.43±0.11 ng/mL),low dose group(0.47±0.10 ng/mL),moderate dose group(0.39±0.11 ng/mL) and high dose group(0.32±0.11 ng/mL)were lower than those of model control group(0.65±0.12 ng/mL,P<0.01).The contents of IL-8 of SMZ/TMP control group(0.33±0.12 ng/mL)were lower than those of model control group (P<0.01).The inflammation of lung tissue was more significantly lightened in treatment group than that in model control group,and the number of foamy exudates in alveolar sacs was obviously fewer.ConclusionBai has immunological regulation effect in PCP treatment in rats and may decrease the content of TNF-and IL-8,which may lighten the inflammation of lung tissue in PCP rats.