Resistance of HIV-infected macrophages to CD8+ T lymphocyte–mediated killing drives activation of the immune system

KL Clayton, DR Collins, J Lengieza… - Nature …, 2018 - nature.com
Nature immunology, 2018nature.com
CD4+ T lymphocytes are the principal target of human immunodeficiency virus (HIV), but
infected macrophages also contribute to viral pathogenesis. The killing of infected cells by
CD8+ cytotoxic T lymphocytes (CTLs) leads to control of viral replication. Here we found that
the killing of macrophages by CTLs was impaired relative to the killing of CD4+ T cells by
CTLs, and this resulted in inefficient suppression of HIV. The killing of macrophages
depended on caspase-3 and granzyme B, whereas the rapid killing of CD4+ T cells was …
Abstract
CD4+ T lymphocytes are the principal target of human immunodeficiency virus (HIV), but infected macrophages also contribute to viral pathogenesis. The killing of infected cells by CD8+ cytotoxic T lymphocytes (CTLs) leads to control of viral replication. Here we found that the killing of macrophages by CTLs was impaired relative to the killing of CD4+ T cells by CTLs, and this resulted in inefficient suppression of HIV. The killing of macrophages depended on caspase-3 and granzyme B, whereas the rapid killing of CD4+ T cells was caspase independent and did not require granzyme B. Moreover, the impaired killing of macrophages was associated with prolonged effector cell–target cell contact time and higher expression of interferon-γ by CTLs, which induced macrophage production of pro-inflammatory chemokines that recruited monocytes and T cells. Similar results were obtained when macrophages presented other viral antigens, suggestive of a general mechanism for macrophage persistence as antigen-presenting cells that enhance inflammation and adaptive immunity. Inefficient killing of macrophages by CTLs might contribute to chronic inflammation, a hallmark of chronic disease caused by HIV.
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