LPS comprises a major PAMP and is a key target of the immune system during bacterial infection. While LPS can be recognised by innate immune cells via the TLR4 complex, it is unknown whether T lymphocytes, especially CD8+ T cells are also capable of doing so. We report here that naïve human CD8+ T cells, after activation by TCR stimulation, express surface TLR4 and CD14. These activated CD8+ T cells can then secrete high concentrations of IFN-γ, granzyme and perforin in response to LPS. These effects can be specifically inhibited using siRNA for TLR4. Furthermore, LPS can synergise with IL-12 to polarise the CD8+ T cells into cytotoxic T-cell 1 (Tc1) that produce IFN-γ but not IL-4, with or without TCR activation. Moreover, CD8+CD45RO+ memory T cells constitutively expressed TLR4 and markedly enhanced IFN-γ production when stimulated with LPS. In contrast, activated murine CD8+ T cells lack TLR4 and CD14 expression and fail to respond to LPS for proliferation and cytokine production. Thus, human but not murine CD8+ T cells are able to directly recognise bacterial LPS via LPS receptor complex and TLR4 provides a novel signal for the activation of effector and memory human CD8+ T cells. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Komia-Koma, M., Gildchrist, D. S., & Xu, D. (2009). Direct recognition of LPS by human but not murine CD8+ T cells via TLR4 complex. European Journal of Immunology, 39(6), 1564–1572. https://doi.org/10.1002/eji.200838866