Practically speaking, the amount of IFN-gamma that is used for most in vitro studies varies depending upon the source of the recombinant preparation of the IFN. From a reliable source (R & D), one can use between 5 ng-20 ng/ml. Higher amounts may lead to cell cycle-related alterations in epithelial cell types. For CD4 positive cells range may be higher (10-50 ng/ml).

Thank you Prof. Choubey!