Immunosenescence is a process in which the immune system weakens and changes its structure with age, affecting both innate and adaptive immunity. The research team investigated five soluble factors in the blood (sCD28, sCD40L, sCD25, IL-6 and sPD-1) as potential biomarkers of this aging process of the immune system. The study included 131 healthy subjects divided into four age groups from young people (≤ 44 years) to elderly people (> 70 years). The results showed that the levels of PD-1, IL-6 and sCD28 increase with age, and IL-6 had the highest individual diagnostic potential with a sensitivity of 71% and a specificity of 78%. However, the combined detection of all three factors (sPD-1, IL-6 and sCD28) improved the diagnostic accuracy to an AUC level of 0.82 with a sensitivity of 70% and a specificity of 80%. The authors conclude that these three biomarkers have the highest diagnostic potential for the detection of immunosenescence, and their joint measurement provides a more accurate prediction of immune aging than individual markers.