VIRUSES AND THE VERSATILE MACROPHAGE

Mononuclear phagocytes, including circulating monocytes and tissue macrophages, play a central role in resistance to viruses. This resitance can be expressed both non-specifically, and specifically in indiction, regulation and amplification of humoral and cell mediated immune responses to viruses. These lead to the extrinsic effect of macrophages on other virus-infected cells or free virus, and the intrinsic effect on viruses within macrophages. While these interactions usually appear to be protective, immunopathologic consequences as well as macrophage dysfunctions have also been noted. The outcome of any given interaction (viral elimination, peristance, latency or transformation) varies markedly with the type of macrophage. The molecular mechanisms involved in these very diverse macrophage-virus interactions are currently under study.