Relevance of gamma interferon, tumor necrosis factor alpha, and interleukin-10 gene polymorphisms to susceptibility to Mediterranean spotted fever.

Several studies have demonstrated that cellular immunity plays a critical role in the protective immune response against Rickettsia conorii. Immune CD4+ and CD8+ T cells are both involved in the control of rickettsial infection (38). Perivascular infiltrated CD4+ and CD8+ T lymphocytes, macrophages, and natural killer cells produce chemokines and cytokines that activate endothelial rickettsicidal activities. Infected human cells, including endothelial cells, hepatocytes, and macrophages, activated by gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β), kill intracellular rickettsiae by one or a combination of three mechanisms, involving nitric oxide syn…