Extrathymic Development of Murine T Cells Post–Bone Marrow Transplant

T cell generation is impaired following allogeneic bone marrow transplantation because the thymus is damaged, and T cell reconstitution takes considerable time. Medical oncologist Marcel van den Brink  describes results published in the December 2012 Journal of Clinical Investigation indicating that functioning T cells may be generated outside the thymus – in abdominal (mesenteric) lymph nodes  – post–allogeneic bone marrow transplant. Using a murine transplant model, van den Brink and colleagues showed that these extrathymic T cells were functional (capable of mounting an immune response) and could provide resistance against a viral infection. Van den Brink explains that these discoveries may open the door for boosting T cell function in patients with allogeneic bone marrow transplant through targeting this (until now unrecognized) alternative mechanism for T cell reconstitution.