Biology of CD34⁺CD38^- cells in lymphohematopoiesis

Since the discovery of the CD34 stem/progenitor cell antigen, considerable progress has been made in further purifying human lymphohematopoietic stem cells (HSC). These studies have identified a number of antigens which can be targeted to subfractionate the CD34⁺ cell population. In particular, several lines of evidence suggest that the rare CD38^- subpopulation of CD34⁺ cells may be enriched in HSC. This review briefly summarizes relevant knowledge concerning the CD38 molecule and the results of in vitro and in vivo studies of CD34⁺38^- cells. Possible clinical uses for purified CD34⁺38^- cells are outlined.