The HIT2 antibody is specific for human CD38, a 45 kD type II transmembrane glycoprotein expressed on thymocytes, activated T and B cells, and monocytes as well as other non-hematopoietic cells. CD38 is an ectoenzyme that functions to catalyze the synthesis and hydrolysis of cyclic ADP-ribose and is involved in cell signaling, regulating cell adhesion, and activation. Additionally, CD38 has been shown to be a prognostic marker for some leukemias and other diseases.