CHANGES IN LEUKOCYTES DURING AGING AND MECHANISMS OF IMMUNOSENENCE

Immunosenescence is a complex biological process that represents the functional and structural decline of the immune system associated with aging. This phenomenon significantly weakens the body's response to infections, tumors, and vaccines, leading to increased morbidity and mortality in the elderly [1]. Leukocytes, in particular lymphocytes and phagocytes, are the main elements of immunosenescence, and changes in their quality, quantity, and functional activity lead to age-related degradation of the entire immune system [2]. The stimulation of T lymphocytes by the thymus (thymocyte involution), the decrease in clonal diversification of B lymphocytes, as well as the transition of aged lymphocytes to a senescent state reduce the effectiveness of the immune response [3]. At the molecular level, immunosenescence is mediated by multiple mechanisms, including accumulation of DNA damage, telomere shortening, protein misfolding, mitochondrial dysfunction, and chronic secretion of inflammatory cytokines (inflamm-aging) [4].