Subsets of CD8 +, CD57+ cells in normal, healthy individuals: correlations with human cytomegalovirus (HCMV) carrier status, phenotypic and functional analyses

Authors


Eddie C. Y. Wang, Department of Medicine, University of Wales College of Medicine, Heath Hospital, Cardiff CF4 4XN, UK.

SUMMARY

Two different subsets of CD8 +, CD57+ cells have been defined, one expressing high levels (CD8high+(CD57+)), the other expressing low levels of surface CD8 (CD8low+(CD57+)). Increased numbers of CD8high+(CD57+) cells correlated with previous HCMV infection. By three-colour fluorescence analysis, the CD8high+(CD57 +) population expressed T cell markers such as CD3 and CD5, and most were αβ T cell receptor (αβ TCR)-positive. A significant proportion also expressed CD71 (transferrin receptor) and MHC class II, although little if any CD25 (IL-2R-p55). Some (≥ 40%) co-expressed CD45RA and CD45RO. The CD8low+ (CD57+) population expressed classical natural killer (NK) cell markers—CD2, CD16 and CD56. The two subsets were also functionally distinct; CD8high+ (CD57+) cells suppressed pokeweed mitogen (PWM)-driven, but not phytohaem-agglutinin (PHA)-driven proliferation and immunoglobulin production; CD8low+ (CD57+) cells exhibited NK cytotoxic activity which was not increased by interferon-alpha (IFN-α). Supernatant from cultured CD8high+ (CD57+) cells suppressed PWM-driven immunoglobulin production, but not proliferation, and this effect was abrogated by physical separation with tissue culture inserts. Thus, a T cell subset expressing activation and memory T cell markers with direct non-specific suppressor activity was present in peripheral blood mononuclear cells (PBMC) of healthy subjects with asymptomatic HCMV infection.

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