Étude du profil immunitaire de sujets âgés hospitalisés en unité de court séjour gériatrique

Abstract

Immunosenescence embraces the whole of age-induced changes observed in the immunomodulatory functions of a living organism, and is mostly characterized by a decrease in cell-mediated immunity and important modifications of the immunological repertoire. The impact of the pathology on ageing immunity is poorly understood and few data are available on the immunological status of old polypathological patients. We report the results of a prospective study aiming at characterizing several established immunological parameters in patients of 75 years old or more, and admitted for diverse pathologies in a unit of acute geriatric ward. Among the 51 included patients (35 women and 16 men), 90% displayed poly-pathologies. We found a prevalence of 86% of immunological abnormalities, with lymphopenia among 41% of the patients (<1500/mm(3)) and abnormal lymphocytes phenotypes among 95% of the oldest patients (>85 years). A strong skewing towards memory T lymphocytes (CD45RO+) over naive T lymphocytes (CD45RA+) was found in 80% of the cases and inverted CD4/CD8 T cells ratio was observed in 12% of our patients. Vitamin D insufficiency (<30ng/ml), which is frequent among the patients (94%), is a predictive factor for T and B cell lymphopenia. Immunological abnormalities are frequent in this frail population and lymphopenia, in particular, could constitute a reinforcing factor of fragility. Vitamin D deficiency could also affect elderly patients' immunity.