The potential to express or suppress human interleukin-2 and interferon-γ genes is not restricted to distinct cell subsets

Cell surface markers CD4, CD8, Leu8 and Leu15 (CD11) were used to separate human lymphoid cell subsets with monoclonal antibody-coated immunomagnetic beads. We show that each of these subsets is able to suppress the induction of IL-2 and IFN-γ genes effectively. This is manifested by a pronounced superinduction of IL-2 and IFN-γ mRNA, as well as IFN-γ protein, in cell populations depleted of one of these subsets. Co-culture of cell subsets with total cell populations or depleted ones, on the other hand, leads to severe inhibition of expression of these genes. In these experiments, cells in suppressor subsets exhibit little, if any, expression of IL-2 and IFN-γ genes. By contrast, depending on donor and lymphoid tissue examined (tonsils or peripheral blood mononuclear cells), CD4, CD8, Leu8, and Leu15 cell subsets are also able to express IL-2 or IFN-γ genes to high levels. Moreover, in Leu8⁺ cells that do not express the IFN-γ gene, extensive expression of both mRNA and protein can be elicited by inhibiting the activation of suppressor cells with γ -irradiation before induction. These results support the concept that the potential to express or suppress human IL-2 and IFN-γ genes is not restricted to distinct cell subsets. Suppression or expression can be elicited in cells carrying a given surface marker, depending on the state of the immune system in a lymphoid tissue.     

Cytokine gene expression in human peripheral blood mononuclear cells stimulated by mannoprotein constituents from Candida albicans.

The expression of cytokine genes in cultures of human peripheral blood mononuclear cells (PBMC) stimulated with mannoprotein constituents (MP) of Candida albicans has been studied by means of S1 nuclease mapping analysis, polymerase chain reaction, and enzyme-linked immunosorbent assay. MP induced early, consistent, and long-lasting production of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha, and IL-6 mRNAs. Similar results were obtained when the same PBMC cultures were stimulated with the purified protein derivative (PPD) from Mycobacterium tuberculosis or with IL-2, although lower levels of IL-6 mRNA were detected in IL-2-stimulated cells than in MP- or PPD-stimulated cells. MP, PPD, and IL-2 induced appreciable levels of granulocyte-macrophage colony-stimulating factor and gamma interferon, but only MP and PPD were able to induce IL-2 mRNA. MP were unable to stimulate a consistent expression of the genes encoding for IL-4, IL-5, and IL-10, while low, sometimes barely detectable levels of these cytokine mRNAs were observed in PPD- or IL-2-stimulated PBMC cultures. When protein synthesis of MP-stimulated PBMC was inhibited by cycloheximide, a superinduction of mRNAs for IL-4 and IL-10 and, more markedly, gamma interferon was observed. Overall, these results highlight the powerful, selective induction of cytokine gene expression by MP constituents of C. albicans in human PBMC cultures, thus providing some functional clues to explain the efficient state of the anticandidal response in normal human subjects.     

genistein对人卵巢癌细胞系SKOV3及其裸鼠移植瘤中表皮生长因子受体介导的信号转导通路的影响

目的　通过 genistein对人卵巢癌细胞系SKOV3 及其裸鼠移植瘤中表皮生长因子受体(EGFR)介导的肿瘤信号转导系统的影响 ,探讨其抑制增殖作用的机制。方法　应用免疫细胞化学链霉素抗生物素蛋白过氧化物酶 (SP)法检测c erbB 2蛋白的表达 ;Western印迹检测细胞c jun和c fos蛋白的表达 ;逆转录 聚合酶链反应 (RT PCR)检测c erbB 2 ,c raf 1,c jun和c fosmRNA的表达。结果　 2 0 μmol/Lgenistein处理组c erbB 2、c raf 1及其下游基因c jun、c fosmRNA表达减弱。2 0 μmol/Lgenistein处理SKOV3 细胞 4 8h后 ,c erbB 2蛋白表达减弱 ,平均吸光度 (A)值减低 ,为0 4 2± 0 0 2 (P <0 0 5 )。Western印迹检测结果表明 :2 0 μmol/Lgenistein处理SKOV3 细胞 12～ 72h后 ,c jun、c fos蛋白表达水平逐渐减弱。结论　genistein下调SKOV3 中EGFR介导的肿瘤信号转导通路中两个关键基因c erbB 2和c raf 1之mRNA及蛋白及其下游核转录因子c jun和c fos的mRNA及蛋白的表达水平 ,提示genistein干预EGFR介导的肿瘤信号转导系统中主要信号分子的表达可能是其抑制卵巢癌增殖的分子基础。