Functional analysis of the CD8(+)CD57(+) cell population in normal healthyindividuals and matched unrelated T-cell-depleted bone marrow transplant recipients

The biological activities of CD8(+) that co-express CD57 remain poorly defi ned. It is unclear whether all CD8(+) cells have the potential to become CD 57(+) or whether they represent a unique subset with distinct functions. Se veral studies have reported the association between elevated numbers of CD8 (+)CD57(+) and a wide range of clinical disorders such as viral reactivatio n of human cytomegalovirus (HCMV). In this study, we have investigated the relationship between viral reactivation and the effect of diminished interl eukin (IL)-2 production. Using CD8(+) cells isolated from patients at vario us times after allogeneic transplants and in vitro models of HCMV infection , we determined their combined effect on CD8(+)CD57(+). Our results show th at high numbers of CD8(+)CD57(+) correlated with diminished killing of HCMV -infected targets. In addition, we showed a synergistic effect between IL-2 and HCMV in the expansion of CD8(+)CD57(+) cells. Furthermore, these cells after anti-CD3 stimulation did not produce tumour necrosis factor (TNF)-al pha or interferon (IFN)-gamma. Interestingly, IL-10 production was elevated in several patients which appeared to be associated with the time from tra nsplant.