Fig. 3

Antigen presenting cells responses in young, old non-frail and old-frail patients. Mixed Lymphocytes Reaction assays were performed to evaluate the antigen-presenting-cells (APCs) capacity based on a T-cells proliferative response of healthy donor PBMCs. The results for the MLR were expressed in terms of cell proliferation quantified by the stimulation index (SI). SI ≥ 3 indicated a positive response and SI < 3 indicated no response. Statistical differences were assessed using Chi-square tests and p < 0.05