The response of intestinal stem cells and epithelium after alemtuzumab administration.

Intestinal stem cells may have important roles in the maintenance of epithelial integrity during tissue repair. Alemtuzumab is a humanized anti-CD52 lymphocytic antibody that is increasingly being used to induce immunosuppression; intestinal barrier function is impaired during treatment with alemtuzumab. We investigated the response of intestinal stem cells to epithelial damage resulting from alemtuzumab treatment. Intestinal epithelial cell loss and abnormal Paneth cell morphology were found following a single dose of alemtuzumab. The animals receiving alemtuzumab exhibited increased apoptosis in the villi 3 days after alemtuzumab treatment and in the crypt on day 9, but apoptosis was scarce on day 35. We assessed expression of Musashi-1- and Lgr5-positive stem cells following alemtuzumab treatment. Increased numbers of cells staining positive for both Musashi-1 and Lgr5 were found in the stem cell zone after alemtuzumab treatment for 3 and 9 days. These data indicated that the epithelial cells were injured following alemtuzumab treatment, with the associated expansion of intestinal stem cells. After alemtuzumab treatment for 35 days, the numbers of intestinal epithelial cells and intestinal stem cells returned to normal. This study suggests that alemtuzumab treatment induced the increase in stem cells, resulting in the availability of more enterocytes for repair.