Expression of α4β7 integrin on memory CD8(+) T cells at the presentation of acute intestinal GVHD.

Acute intestinal GVHD remains a major source of morbidity after allogeneic hematopoietic cell transplantation (HCT). α4β7 integrin is a cell surface molecule that mediates lymphocyte trafficking to intestinal tissue. In this analysis, peripheral blood was collected at the time of presentation of symptoms of acute GVHD and before any treatment. In all, 45 samples were collected and divided into three groups on the basis of subsequent evaluation: intestinal GVHD (n=15), skin GVHD (n=20) and no GVHD (n=10). Two patients developed intestinal GVHD after DLI. The no-GVHD group comprised 10 patients who presented with suspicious symptoms, but evaluation yielded other etiologies. Analysis by flow cytometry showed that intestinal GVHD patients had a significantly higher percentage of α4β7 integrin-expressing memory CD8(+) T cells (median 7.69%; lower and upper quartiles, 1.06% and 11.64%, respectively) compared with patients with skin GVHD (1.26%; 0.57% and 2.49%) and no GVHD (0.96%; 0.44% and 1.85%), P=0.03. No differences were found in α4β7 expression in any CD4(+) T-cell subsets or naive CD8(+) T cells. This study adds to the evidence that α4β7 integrin is involved in lymphocyte trafficking in acute intestinal GVHD.