Uptake of extracellular Ca2+ is a requirement for production of interferon-gamma by cord blood mononuclear cells.

We studied the response of adult peripheral and cord blood mononuclear cells (MNCs) to graded concentrations of phytohemagglutinin (PHA) to characterize the requirements for proliferation and interferon-gamma (IFN-gamma) production. As the concentration of PHA was decreased, the proliferative response of both adult and cord blood MNCs decreased in parallel. At high concentrations of PHA (a: 120) cord blood MNCs display normal high proliferation but IFN-gamma production was greatly diminished compared with adult MNCs. Addition of the calcium ionophore, A23187, to PHA-stimulated adult MNCs had no effect on proliferation or IFN-gamma production at any of the concentrations of PHA tested. Furthermore, A23187 alone had no effect on proliferation or IFN-gamma secretion. Similarly, the addition of A23187 to PHA-stimulated cord-blood MNCs had no effect on proliferation. However, when A23187 was added to high dose (1:120) PHA-stimulated cord blood MNCs IFN-gamma production increased to levels comparable with adult PHA-stimulated MNCs. A similar pattern of response was seen when exogenous calcium chloride was added in place of A23187.