https://www.selleckchem.com/products/colcemid.html Severe respiratory viral infectious diseases such as influenza and COVID-19 especially affect the older population. This is partly ascribed to diminished CD8+ T-cell responses a result of aging. The phenotypical diversity of the CD8+ T-cell population has made it difficult to identify the impact of aging on CD8+ T-cell subsets associated with diminished CD8+ T-cell responses. Here we identify a novel human CD8+ T-cell subset characterized by expression of Killer-cell Immunoglobulin-like Receptors (KIR+ ) and CD45RA (RA+ ). These KIR+ RA+ T cells accumulated with age in the blood of healthy individuals (20-82 years of age, n = 50), expressed high levels of aging-related markers of T-cell regulation, and were functionally capable of suppressing proliferation of other CD8+ T cells. Moreover, KIR+ RA+ T cells were a major T-cell subset becoming activated in older adults suffering from an acute respiratory viral infection (n = 36), including coronavirus and influenza virus infection. In addition, older adults with influenza A infection showed that higher activation status of their KIR+ RA+ T cells associated with longer duration of respiratory symptoms. Together, our data indicate that KIR+ RA+ T cells are a unique human T-cell subset with regulatory properties that may explain susceptibility to viral respiratory disease at old age. It is unclear to what extent a board certification system and implementation of clinical guidelines improves the quality of hepatectomy. A web-based questionnaire survey was administered to departments registered with the National Clinical Database (NCD) in Japan between 1 October 2014 and 31 January 2015. Quality indicators (QIs), including affiliations with academic societies, numbers of board-certified doctors affiliated with each institute, and adherence to clinical practice guidelines for hepatocellular carcinoma, were evaluated by calculating risk-adjusted odds ratios (AORs) for 90-day