Interferon-alpha and interferon-gamma as regulators of human adult and newborn B-cell function

The role of interferon-alpha (IFN-alpha) and interferon-gamma (IFN-gamma) in the regulation of B-cell function was studied using highly purified tonsillar B-cells and unfractionated mononuclear cells from healthy adults and newborns. Recombinant IFN-gamma (rIFN-gamma) was found to enhance Staphylococcus aureus Cowan I (SAC)-induced proliferation of purified B-cells. Recombinant IFN-alpha (rIFN-alpha) neither enhanced nor inhibited the function of purified B-cells. However, when unfractionated mononuclear cells were studied, no enhancement in SAC- or pokeweed mitogen (PWM)-induced proliferation was found in response to these IFNs. In fact, the responses in these cultures were mainly inhibitory. The effects were dependent on the mitogen used for activation of the cells and on the source of the cells. The IFNs acted in a more inhibitory way in cultures stimulated with PWM than in those stimulated with SAC. In addition, they acted more suppressively in cord blood mononuclear cells (CBMCs) than in adult peripheral blood mononuclear cells. PWM was found to decrease CD4+/CD8+ T-cell ratio, and cells with suppressor function physiologically dominate among CBMCs. Thus, the effect of these interferons on B-cell function seems to depend on the magnitude of suppressor cell function among the cell population.