One of the mechanisms that characterizes the aging process of different organs is the accumulation of fat. Different authors have demonstrated that adipose tissue replaces the loss of other cell types, deriving from mesenchymal cells. During aging, there is substitution or trans-differentiation of mesenchymal cells with other cells having the same embryological origin. Newly formed adipocytes were also observed in the trabecular matrix of elderly people’s bones, associated with myeloid cells. In this study, we have investigated the relationship between immature myeloid-derived suppressor cells (I-MDSCs) and mesenchymal stem cells (MSCs) in bone marrow (BM) samples harvested from 57 patients subjected to different orthopedic surgeries. Patients aged from 18 to 92 years were considered in order to compare the cellular composition of bone marrow of young and elderly people, considered a biomarker of immunity, inflammation, and bone preservation. The I-MDSC percentage was stable during aging, but in elderly people, it was possible to observe a strong basal immunosuppression of autologous and heterologous T cells’ proliferation. We hypothesized that this pattern observed in elders depends on the progressive accumulation in the BM of activating stimuli, including cell–cell contact, or the production of different cytokines and proteins that induce the differentiation of bone marrow mesenchymal stem cells in adipocytes. The collected data provided underline the importance of specific biomarkers of aging that promote a reduction in immune response and incremented inflammatory pathways, leading to bone reabsorption in elderly people.

T cell–dependent bispecific antibodies (TCB) are a potent class of therapeutic molecules that redirect the cytotoxic activity of CD8+ T cells against target cells by engagement of CD3 and a tumor antigen. In vitro functional screening of TCBs often relies on endpoint readouts of activity that fail to capture the kinetics of T-cell activation. The lower throughput of traditional T-cell killing assays also poses challenges in assessing TCB potency and efficacy against tumor cell lines varying in target expression level and across a range of effector-to-target cell ratios. In this study, we describe the development of an automated, high-throughput (HT) T cell–dependent in vitro cytotoxicity assay that enables kinetic and multiparametric assessment of T-cell killing and cytokine production. We applied this assay to determine the functional activity of TCBs against hematologic and solid tumor targets, including molecules that bind to different tumor antigens and CD3 epitopes. Moreover, we incorporated a set of data analysis and visualization tools to integrate multiple parameters of T-cell activity and classify TCBs into distinct subsets. We expanded the platform to screen costimulatory receptor agonist antibodies that combine with TCBs to enhance antitumor activity. Taken together, our approach comprises a novel combination of biological, technical, and analytic methods to characterize T-cell functional activity. This method enables robust and HT assessment of TCBs and combination therapies and enhances the selection of lead candidates with distinct characteristics for further development.