Abstract
Graft-versus-host disease (GvHD) is a common, morbid complication after intestinal transplantation (ITx) with poorly understood pathophysiology. Resident memory T cells (T(RM) ) are a recently described CD69+ memory T cell subset localizing to peripheral tissue. We observed that T effector memory cells (T(EM) ) in the blood increase during GvHD and hypothesized that they derive from donor graft CD69+T(RM) migrating into host blood and tissue. To probe this hypothesis, graft and blood lymphocytes from 10 ITx patients with overt GvHD and 34 without were longitudinally analyzed using flow cytometry. As hypothesized, CD4+ and CD8+CD69+T(RM) were significantly increased in blood and grafts of GvHD patients, alongside higher cytokine and activation marker expression. The majority of CD69+T(RM) were donor derived as determined by multiplex immunostaining. Notably, CD8/PD-1 was significantly elevated in blood prior to transplantation in patients who later had GvHD, and percentages of HLA-DR, CD57, PD-1, and naïve T cells differed significantly between GvHD patients who died vs. those who survived. Overall, we demonstrate that (1) there were significant increases in T(EM) at the time of GvHD, possibly of donor derivation; (2) donor T(RM) in the graft are a possible source; and (3) potential biomarkers for the development and prognosis of GvHD exist.