Low burst promoting activity production by phytohemagglutinin-stimulated mononuclear cells of cord blood

Burst-promoting activity (BPA) produced by phytohemagglutinin(PHA)-stimulated cord blood mononuclear cells (MNC) was examined using the two-stage cell culture assays. Burst-promoting activity was measured as the increase in the number of early erythroid progenitor cells in 2-day incubation of peripheral blood MNC with or without the conditioned medium of PHA-stimulated MNC (PHA-LCM). Burst-promoting activity in PHA-LCM of cord blood was significantly lower than that of adult blood (37 +/- 13 versus 105 +/- 19%, mean +/- SD, p less than 0.01). No elevation of inhibitors to the erythroid colony growth was noted in PHA-LCM of cord blood. In contrary, the response of cord blood MNC to PHA was similar to that of adult blood MNC, as determined by colony-stimulating activity production and cell proliferation. These results showed that burst-promoting activity production by PHA-stimulated MNC of cord blood was lower than that of adult blood.