Flow cytometric measurement of intracellular IFN-gamma induction in aged subjects before and after parenteral influenza vaccination.

Flow cytometric analysis, used to study intracellular expression of IFN-gamma in peripheral blood mononuclear cells (PBMC) from aged volunteers before and after parenteral influenza vaccination, was found capable of rapidly detecting influenza antigen induced variation of IFN-gamma expression. Although the vaccine was capable of generating a satisfactory antibody response, it did not stimulate an increase in the percentage of IFN-gamma positive cells.