 Sepsis syndrome is frequently complicated by the development of nosocomial infections, particularly Gram-negative pneumonia. Findings indicate that TLR9 serves as an important signal in the generation of protective innate responses to bacterial pathogens of the lung and that is required for effective innate immune responses against Gram-negative bacterial pathogens. Unmethylated CpG motifs are prevalent in bacterial but not vertebrate genomic DNA. The recognition of CpG motifs activates host defense mechanisms leading to innate and acquired immune responses. Cells that express TLR-9 are the plasmacytoid dendritic cells PDCs and the B cells and as a consequences produce Th1-like proinflammatory cytokines, interferons and chemokines. Activation of TLR-9 induces the production of a cytokines IL-12, IL-1, IL-6, IL-8, interferon IFN-γ and tumor necrosis factor TNF-α which are Th1 proinflammatory cytokines and b IL-10 and IL-4 which are Th2 proinflammatory cytokines that induce immunosuppression. 