RESUMO
Urine from a patient with cyclic neutropenia was found to contain a lymphopoietic activity that acts as a growth factor for human pre-B cells. This biologic activity was detectable during the week preceding, but not during, the period of neutropenia. This corresponded with a periodic excessive accumulation of pre-B cells in the marrow of this patient. Urine preparations were added to cultures of normal human bone marrow that had been depleted of B cells. Pre-B cells were generated in these cultures but not in cultures containing urine preparations from normal donors. Pre-B cells were also generated from bone marrow that had been depleted of 177.17+ cells and the majority of pre-B cells. This is the first report of a hemopoietic activity which affects human pre-B cells. This activity may represent a normal regulatory molecule that is periodically produced in excess in this patient.
