CD4+ and CD8+ T Cells in Murine Virus Infections: Experiments with Lymphocytic Choriomeningitis and Influenza

Abstract

Much of the analysis of T cell function in virus-specific cellmediated immunity [CMI] in the mouse has concentrated on the CD8+, class I major histocompatibility complex [MHC] restricted effector population. Part of the reason for this is that the early cytotoxic T lymphocyte [CTL] assays were done only with class I MHC+, virus-infected taget cells [Zinkernagel and Doherty, 1979]. Also, it was apparent from the initial adoptive transfer experiments with the lymphocytic choriomeningitis [LCM] model that both the induction of inflammation in the central nervous system [CNS] and the promotion of virus clearance from extraneural sites were properties of the class I MHC-restricted T cell subset. Compatibility between donor and recipient for class II MHC phenotype alone was without effect [Doherty et al, 1976]. The paradigm that developed was that the class I MHC restricted effectors were particularly concerned with viruses, or with any agent that could directly modify the surface of the cell, while the class II MHC restricted population would be targeted principally to macrophages or to other cells having the capacity to phagocytose exogenous material. It is now apparent that antigen processing is essential in both cases, though the net result is still partitioning of the response as a consequence of the intracellular sites where protein degradation occurs [Yewdell and Bennink, 1989] The following discusses our current understanding of the respective roles of CD8+ class I MHC-restricted and CD4+ class II MHC restricted T cells in the mouse influenza and LCM models, and describes some recent phenotypic and functional studies of influenza pneumonia.