Dysregulated T helper type 1 (Th1) and Th17 responses in elderly hospitalised patients with infection and sepsis.

OBJECTIVE:The role of Th1 and Th17 lymphocyte responses in human infection and sepsis of elderly patients has yet to be clarified. DESIGN:A prospective observational study of patients with sepsis, infection only and healthy controls. SETTING:The acute medical wards and intensive care units in a 1000 bed university hospital. PATIENTS:32 patients with sepsis, 20 patients with infection, and 20 healthy controls. Patients and controls were older than 65 years of age. Patients with recognised underlying immune compromise were excluded. METHODS:Phenotype, differentiation status and cytokine production by T lymphocytes were determined by flow cytometry. MEASUREMENTS:The differentiation states of circulating CD3+, CD4+, and CD8+ T cells were characterised as naive (CD45RA+, CD197+), central memory (CD45RA-, CD197+), effector memory (CD45RA-, CD197-), or terminally differentated (CD45RA+, CD197-). Expression of IL-12 and IL-23 receptors, and the transcription factors T-bet and RORγt, was analysed in circulating T lymphocytes. Expression of interferon- γ and IL-17A were analysed following stimulation in vitro. RESULTS:CD4+ T cells from patients with infection predominantly expressed effector-memory or terminally differentiated phenotypes but CD4+ T cells from patients with severe sepsis predominantly expressed naive phenotypes (p