Abstract:In this study,the effects of stimulation with LPS on inflammatory cyokines in the alveolar macrophages(AM)of rats with Pneumocytis carinii pneumonia(PCR)were investigated,and the possible role of these cytokines in th modulation relationship and the immuno-regulatory effects on AM of rats with PCR were evaluated.LPS was added to the cell culture system to stimulate expression of cytokine genes,and cells harvested at 1,4,8 and 24 hours,total RNA extracted,and the mRNA expressions of C/EBP ε IL-6,INF-α were determined by semiquantitative RT-PCR.It was found that the mRNA expressions of IL-6 and TNF-α after stimulation with LPS were significantly enhanced in 1-24 hours.The expression of CCAAT/enhancer-binding protein ε (C/EBP ε)mRNA showed a tendency of graduate increase,with a peak time at 8 hours after stimulation,and the peak time of expression of C/EBP ε mRNA was somewhat delayed in comparison with those of TNF-α and IL 6.It concludes that LPS can stimulate the alveolar macrophages of rats with PCP to produce cytokines with immunological activities,such as TNF-α and IL 6,that can act as biological signal of positive feedback up stream gene to up regulate further the expression of C/EBF.