Preexposure of resting B cells to interferon-gamma enhances their proliferative response to subsequent activation signals.
In this report we demonstrate that pretreatment of resting splenic B cells with IFN-gamma increases their mitogenic response to subsequent activating stimuli. This effect is completely blocked by neutralizing anti-IFN-gamma antibodies. By contrast, a similar effect induced by partially purified BCGF is not completely inhibited by anti-IFN-gamma antibody, inferring that as in the mouse, a B-cell-specific factor may also induce increased responsiveness to mitogens in resting B cells. The mechanism of this response was analyzed. Phenotypic and cell cycle analyses of the IFN-gamma-treated cells following activation were not significantly different from control cells with respect to kinetics, although as expected from thymidine uptake, more cells were actively cycling. Even when a very early manifestation of cell activation, Ca2+ flux was examined, no response to IFN-gamma alone was evoked, and the response to subsequent activation was identical to that of control cells. These data show that IFN-gamma did not directly activate B cells, but primed B cells in a manner which amplified subsequent mitogenesis.
Boyd, AW; Tedder, TF; Griffin, JD; Freedman, AS; Fisher, DC; Daley, J; Nadler, LM
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