In the in vitro portion of the study, researchers used mouse bone marrow cells containing the stem cells that give rise to mast cells. They cultured these precursor cells in conditions that allow mast cells to develop, and then added IFNγ to some of these cultures. A high rate of cell death yielding no living mast cells was observed in the cultures that received IFNγ.
Similar results were reported in vivo using a mouse model. Mice with a mutation that causes them to overproduce IFNγ were used, and again, researchers observed a significant decrease in mast cell numbers due to the excess of IFNγ. When researchers tried to culture mast cells from the bone marrow of these mice, the mast cells died.
Furthermore, a separate strain of mice with the same mutation as the first strain, but that had also been engineered to prevent IFNγ production, were found to have almost as many mast cells as normal mice, if not more. They concluded that the presence of high IFNγ levels blocked mast cell development.