T cell cytokine profile during primary Epstein‐Barr virus infection (infectious mononucleosis)

Cytokine profiles of CD4 + and CD8 + T‐cell subsets were evaluated in 8 patients with infectious mononucleosis (IM). Intracellular detection of cytokines using flow cytometry revealed an expansion of IFN‐γ‐expressing CD4 + T cells, and particularly CD8 + T cells, while IL‐2 expressing cells were less frequently encountered when compared to healthy controls. Single TNF‐α‐expressing CD4 + and CD8 + T cells were likewise reduced and shifted towards IFN‐γ\TNF‐α co‐production. The predominant pro‐inflammatory type 1‐biased immune response during IM was emphasized by low frequencies of IL‐10 expression in both T cell subsets, although some patients displayed elevated serum levels. Six months later, a decreased, but still elevated IFN‐γ expression within the CD8 + T cell subset, and an increased percentage of IL‐2‐expressing CD4 + and CD8 + T cells, reaching values shown for controls, were noted. Type 2‐associated cytokines such as IL‐4 and IL‐13, as well as IL‐6 and TNF‐α were not significantly different when compared to controls at study entry and at follow‐up. The striking expansion of IFN‐γ‐producing CD8 + T cells with rather low expression of IL‐10, appears to be a key factor for clinically overt disease, but is nevertheless compatible with successful control of the viral infection.