Cathepsin B controls the persistence of memory CD8 + T lymphocytes

Susan M. Byrne, Anne Aucher, Syarifah Alyahya, Matthew Elder, Steven T. Olson, Daniel M. Davis, Philip G. Ashton-Rickardt

    Research output: Contribution to journalArticlepeer-review


    The persistence of memory T lymphocytes confers lifelong protection from pathogens. Memory T cells survive and undergo homeostatic proliferation (HSP) in the absence of Ag, although the cell-intrinsic mechanisms by which cytokines drive the HSP of memory T cells are not well understood. In this study we report that lysosome stability limits the long-term maintenance of memory CD8 + T cell populations. Serine protease inhibitor (Spi) 2A, an anti-apoptotic cytosolic cathepsin inhibitor, is induced by both IL-15 and IL-7. Mice deficient in Spi2A developed fewer memory phenotype CD44 hiCD8 + T cells with age, which underwent reduced HSP in the bone marrow. Spi2A was also required for the maintenance of central memory CD8 + T cell populations after acute infection with lymphocytic choriomeningitis virus. Spi2A-deficient Ag-specific CD8 + T cell populations declined more than wild-type competitors after viral infection, and they were eroded further after successive infections. Spi2A protected memory cells from lysosomal breakdown by inhibiting cathepsin B. The impaired maintenance of Spi2A-deficient memory CD8 + T cells was rescued by concomitant cathepsin B deficiency, demonstrating that cathepsin B was a physiological target of Spi2A in memory CD8 + T cell survival. Our findings support a model in which protection from lysosomal rupture through cytokine-induced expression of Spi2A determines the long-term persistence of memory CD8 + T cells. Copyright©2012 by The American Association of Immunologists, Inc.
    Original languageEnglish
    Pages (from-to)1133-1143
    Number of pages10
    JournalJournal of Immunology
    Issue number3
    Publication statusPublished - 1 Aug 2012


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