Abstract: | It has been recently demonstrated that macrophages are necessary accessory cells for T-lymphocyte activation by antigens, mitogens and allogenic cells. This paper shows the function of metabolically inactive macrophages in the activation of T-lymphocytes by phytohemagglutinin (PHA). Macrophages inactivated by mitomycin C are unable to collaborate with T-lymphocytes in the development of the proliferative response to PHA indicating that the role of the macrophage in T-lymphocyte activation by mitogens goes beyond insolubilizing it or rendering it more stimulatory by another passive mechanism. |