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CD8+ T cells against extracellular pathogens: more than just a cytotoxic cell
Rafael Cardoso Maciel Costa Silva1
1Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
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The role of CD8+ T cells, as cytotoxic cells, being critical against intracellular pathogens is well known. Through the killing of infected (target) cells, CD8+ T cells impair intracellular pathogens' replication. However, extracellular pathogens are not directly targeted by CD8+ T cells, since these pathogens do not express MHC-I-peptides, responsible for the activation of the cytotoxic activity of CD8+ T cells. In this sense, how CD8+ T cells affect the course of extracellular infections is discussed in this review, underscoring the important regulatory functions of CD8+ T cells, killing phagocytes and other cells that are able to cross-present extracellular antigens. In addition, the role of CD8+ T cells in the modulation of immune responses through the secretion of cytokines, such as gamma interferon (IFNγ), is also discussed in the context of extracellular infections.
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