Early differentiated CD28 + CD27 + T lymphocytes as a biomarker for short and long-term outcomes in older patients with pneumonia.

This study tested the hypothesis that a more senescent immune system would predict a worse outcome in older patients hospitalized for community-acquired pneumonia (CAP). CAP has long been responsible for high rates of mortality and readmissions among older people. Although immunosenescence is a key factor in the increased susceptibility to infections, there are no related biomarkers currently available in clinical practice. In this context, the aim of this prospective study was to identify immunosenescence-related biomarkers to predict outcomes in patients older than 65 years hospitalized for CAP. We evaluated 97 patients admitted to our hospital for CAP in 2019 and 2020. All patients were followed for 1 year. Our findings showed that elevated levels of early differentiated CD28 + CD27 + T cells at admission were associated with better short (2 months) and long-term (1 year) outcomes in terms of mortality and readmissions. Early differentiated CD28 + CD27 + CD4 + T cell counts were even better long-term predictors. In conclusion, early differentiated CD28 + CD27 + T cells could be useful biomarkers to identify high-risk older patients with CAP, helping clinicians with risk stratification and follow-up.