• Godelieve J de Bree, Hans Daniels, Schilfgaarde Muriel van Mv, Henk M Jansen, Theo A Out, Rene A W van Lier, and Rene E Jonkers.
• Department of Pulmonology, Academic Medical Center, Amsterdam, The Netherlands. g.j.debree@amc.uva.nl
• J. Infect. Dis. 2007 Jun 1; 195 (11): 1718-25.

BackgroundWe investigated CD4(+) memory T cell responses to influenza virus (FLU), respiratory syncytial virus (RSV), and nontypeable Haemophilus influenzae (NTHi).MethodsThe precursor frequencies of antigen-specific CD4(+) cells were determined by in vitro expansion of peripheral blood mononuclear cells from healthy individuals (n=9) and patients with chronic obstructive pulmonary disease (COPD; n=16). The expression of CD27 and CCR7 and the production of interferon (IFN)- gamma and interleukin-2 was measured directly ex vivo. Furthermore, the phenotypic and functional properties of CD4(+) T cells residing in the lung were analyzed and compared with those of circulating CD4(+)memory cells from the same donors (n=8).ResultsFLU-, RSV-, and NTHi-specific CD4(+) memory T cells circulated at low frequencies in the peripheral blood of healthy individuals and patients. RSV- and NTHi-specific CD4(+) T cells had a memory phenotype with moderate to high CD27 and CCR7 expression. In contrast to the low frequencies of circulating FLU-specific CD4(+) T cells, we found an enrichment of differentiated CD4(+) FLU-specific cells and high IFN- gamma expression in CD4(+) memory cells in lung tissue.ConclusionNo gross defects were found in circulating CD4(+) memory cells specific for pathogens associated with COPD. However, the large differentiated CD4(+) memory T cell pool residing in the lung may contribute to a large extent to local antiviral immunological protection.

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