Effector memory and late memory T cells accumulate in the blood of CMV-carrying individuals but not in their cerebrospinal fluid.

Cytomegalovirus (CMV)-carrying individuals have significantly higher levels of effector memory and late memory T lymphocytes in their blood than non-carriers. To date, it is well recognized that the central nervous system is subjected to active immunosurveillance, as evidenced by the presence of central memory T cells in cerebrospinal fluid (CSF) of healthy individuals. In order to investigate whether levels of effector memory and late memory T cells were also increased in the CSF of CMV-carrying individuals, we characterized CD4⁺ and CD8⁺ T-cell subsets in CSF and blood of both groups. Effector memory and late memory T cells were only rarely seen in CSF, which was similar in CMV carriers and non-carriers. In conclusion, there was no demonstrable difference in the numbers of CSF effector memory and late memory T cells between CMV seronegative and CMV seropositive individuals.