Respiratory syncytial virus-specific CD8+ memory T cell responses in elderly persons.

BACKGROUND: We investigated respiratory syncytial virus (RSV)-specific CD8(+) memory T cell responses in healthy control participants (n=31) and in patients with chronic obstructive pulmonary disease (COPD) (n=9), with respect to frequency, memory phenotype, and proliferative requirements.
METHODS: The properties of RSV-specific CD8(+) T cells were analyzed by use of RSV tetramers. The proliferative requirements of RSV-specific CD8(+) T cells were analyzed by culture of peripheral-blood mononuclear cells with RSV peptide in combination with distinct cytokines.
RESULTS: RSV-specific CD8(+) memory T cells showed a high level of expression of CD27 and interleukin-7R alpha and a low level of expression of CCR7. In the healthy participants, the frequency of RSV tetramer(+) CD8(+) T cells was significantly lower than the frequency of influenza virus A (FLU) tetramer(+) CD8(+) T cells (P=.0001). In contrast to FLU tetramer(+) CD8(+) T cells, we could detect RSV tetramer(+) CD8(+) T cells in the subgroup of elderly healthy participants (age, > or =55 years) and in the patients with COPD only after in vitro expansion. Expanded RSV-specific T cells produced interferon- gamma and granzyme B.
CONCLUSION: We provide evidence that a pool of functional RSV-specific CD8(+) memory T cells persists in the peripheral blood of healthy individuals and patients with COPD. Low numbers of RSV-specific memory T cells in the elderly and in patients with COPD may explain the increased susceptibility to RSV infection in these populations.