To characterize the multiplica tion of L. pneumophila in human T cells, intracellular growth in CD4 T cells of L. pneumophila was examined. The CFU from the wild type Corby elevated soon after infection for 24 h in CD4 T cells, even though it replicated much less Carbonic Anhydrase effi ciently compared using the observations with Jurkat cells. Staining with the contaminated Jurkat cells for L. pneu mophila showed elevated intracellular replication of AA100jm, Corby, and flaA mutant, but not dotO mutant following 24 h in culture. These observations propose that L. pneumophila can replicate in human T cells and also the sort IV secretion technique plays a function in L. pneumophila replication in human T cells. Substantial serum IL 8 levels in patients with Legionella pneumonia To investigate the role of IL eight from the pathogenesis of Legionella pneumonia, the circulating concentrations of IL eight had been measured.
Serum IL eight amounts were higher in patients with Legionella pneumonia than in ordinary healthful controls, while this big difference was not statisti cally substantial. Hence, we analyzed the signaling pathways for IL 8 activation by Legionalla infection. Infection of Jurkat and CD4 T cells by L. pneumophila induces IL 8 expression Jurkat cells have been infected with wild kind L. pneumophila strains AA100jm and Corby for up to twelve h. Total cellular RNA was isolated from these cells at 0. five, one, 2, 4, six, 8 and twelve h after the infection and IL eight gene expression was ana lyzed by RT PCR. IL eight mRNA expression improved just after the infection. In another series of experiments, in which Jurkat cells had been infected with AA100jm and Corby at distinct concentrations for 4 h, each strains induced dose dependent expression of IL 8 mRNA.
Up coming, we examined the correlation amongst IL eight expression levels as well as the virulence of L. pneumophila. As shown in Fig. 2A, IL eight mRNA expression was induced after infection together with the avirulent dotO mutant, but grew to become progressively weaker from 8 to 12 h. In contrast, a flaA knockout mutant, defective in flagellin manufacturing, failed to induce IL eight mRNA soon after infection. To characterize the effect of L. pneumophila infection on human T cells, IL 8 mRNA expression in CD4 T cells in response to L. pneumophila was examined by RT PCR. Following infection for 3 h, L. pneumophila induced IL 8 mRNA expression in CD4 T cells, very similar to the observa tions with Jurkat cells. To determine the correlation amongst IL 8 expression level and L.
pneumophila bacterial proteins, heat killed Corby was employed to infect Jurkat cells at a multiplicity of infection of 100. At 4 h, IL 8 was not expressed in Jurkat cells contaminated with the heat killed strain. Additionally, IL eight gene expression was not induced when paraformaldehyde fixed L. pneumophila was utilized. However, bacteria heated at 56 C for 30 min induced IL 8 expression. These results recommend the surface proteins of bacteria but not lipopolysac charide are needed for IL 8 induction.