CD38

CD38 is a type II transmembrane ectoenzyme that converts NAD+ into the calcium-mobilizing second messengers cyclic ADP-ribose and ADP-ribose, tying its expression to cellular metabolic state. Although present at low levels on resting lymphocytes, CD38 is strongly induced on activated immune cells and is broadly exploited as an activation marker in flow cytometry and HIV monitoring. It is also displayed at very high density on plasma cell malignancies, which enabled the CD38 antibodies daratumumab and isatuximab to become standard therapies in multiple myeloma. Beyond hematology, its NAD+-depleting activity is studied in aging and metabolic disease.