Peripheral blood lymphocytes resistant to Epstein-Barr virus immortalization manifest high natural killer (NK) type activity against NK-resistant target cells

Regulatory pathways involved in the infection-induced production of IFN-gamma by NK cells

The production of interferon gamma (IFN-gamma) by natural killer (NK) cells provides an innate mechanism of resistance to many intracellular pathogens. These events are regulated by multiple cytokines and transcription factors which have both positive and negative effects. This article reviews the role of cytokines, as well as costimulatory and signaling pathways, involved in NK cell responses associated with resistance to infection.

Infection of peripheral blood mononuclear cells by herpes simplex and Epstein-Barr viruses. Differential induction of interleukin 6 and tumor necrosis factor-alpha

Infection by herpesviruses can result in profound immunosuppressive or immunomodulatory effects. However, no significant information is available on the effect of such infections on the production of immunoregulatory cytokines. We studied the kinetics of production of two monocyte-derived cytokines, interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF alpha), induced by Epstein-Barr virus (EBV) and herpes simplex virus type 1 (HSV-1) in peripheral blood mononuclear cell cultures and in fractionated cell populations. We observed that, when compared to HSV-1, EBV is a stronger inducer of IL-6. In EBV-infected cultures, IL-6 protein was detected at day 1 postinfection and gradually increased with time. In contrast, lower amounts of IL-6 were detected 5 d postinfection in HSV-1-infected cultures. HSV-1-infected cultures secreted significant amounts of TNF alpha protein after 5 d of culture and reached a maximal level of production at day 7, whereas EBV inhibited TNF alpha production. In fractionated cell populations, monocytic cells were found to be the main source of IL-6 synthesis after EBV or HSV-1 infection. However, TNF alpha synthesis in HSV-1-infected cultures was from both B and monocytic cells. By using the polymerase chain reaction technique we show that, after infection by these two herpesviruses, differences in cytokine gene products are also observed at the transcriptional level. These observations demonstrate that EBV and HSV-1 exert differential effects on IL-6 and TNF alpha gene transcription and on the resulting protein secretion in human mononuclear blood cells.