Nocardia water soluble mitogen (NWSM), a human B-lymphocyte mitogen

Nocardia water soluble mitogen (NWSM), which is a peptidoglycan, was prepared from Nocardia opaca. Its effect on human B-lymphocyte proliferation, the number of immunoglobulin secreting B-cells, and bone marrow stem cell growth was studied in vitro. NWSM stimulated the proliferation of B-lymphocytes of all ten healthy subjects studied very effectively (P less than 0.0005). No T-cell activation occurred. NWSM did not increase the amount of antibody producing cells. The growth of bone marrow stem cells was enhanced only in one patient out of the eight studied. Thus NWSM is a B-lymphocyte mitogen with a potential effect on hematopoietic stem cells. However, production of NWSM was faced with difficulties because not all lots prepared had B-cell stimulating activity.