CYTOTOXIC ACTIVITY AGAINST MAEDI-VISNA VIRUS-INFECTED MACROPHAGES

The cell type predominantly infected by maedi-visna virus (MVV) is the macrophage, and we have looked at the ability of MVV-infected macroph ages to interact with cytotoxic T lymphocytes (CTL), important effecto r cells against virus infections. MVV-specific CTL precursors were det ected, after in vitro culture with MVV antigen and recombinant human i nterleukin-2, in peripheral blood lymphocytes of all MW-infefted sheep . MVV-infected monocyte-derived macrophages and alveolar macrophages w ere able to stimulate CTL activity in vitro and were targets far these activated CTL. The major effector cell population using MVV-infected macrophage targets was CD8(+) lymphocytes, although another population , lymphokine-activated killer cells, may also have been involved. Ther e was no direct cytotoxic activity found in alveolar lymphocytes from MVV-infected sheep without lung lesions.