Human Bone Marrow as a Source to Generate CMV-specific CD4(+) T Cells With Multifunctional Capacity

To bone marrow (BM) is an important compartment for T cell memory. In cytomegalovirus (CMV)-seropositive individuals peripheral blood (PB) CMV-specific T cells constitute a large fraction of PB T cells but are mostly differentiated effector/effector memory T cells with limited survival and proliferative potential. In this study, we performed a comprehensive analysis of the CMV-specific T cell response in BM studying both CD4(+) and CD8(+) T cell responses against overlapping peptide pools of the CMV proteins pp65 and immediate early protein-1. CMV-specific T cell responses were characterized ex vivo and after in vitro expansion of paired PB/BM samples by multiparameter flow cytometry determining surface phenotype, cytokine profile, and cytotoxic capability. Comparable frequencies of CMV-specific T cells were found in un-manipulated PB and BM. Both total CD(4+) and CD8(+) T cells could be more rapidly expanded from BM. Expanded BM T cells contained significantly higher frequencies of CMV-specific CD4(+) T cells than PB. Furthermore, higher frequencies of specific CD4(+) T cells from BM were multifunctional characterized by simultaneous production of interfereon-gamma, tumor necrosis factor, and interleukin-2. Use of BM may thus facilitate more rapid generation of adoptive T cells with enhanced functionality.