Intestinal double‐positive CD4+CD8+ T cells are highly activated memory cells with an increased capacity to produce cytokines

B Pahar, AA Lackner, RS Veazey - European journal of …, 2006 - Wiley Online Library
European journal of immunology, 2006Wiley Online Library
Peripheral blood and intestinal CD4+ CD8+ double‐positive (DP) T cells have been
described in several species including humans, but their function and immunophenotypic
characteristics are still not clearly understood. Here we demonstrate that DP T cells are
abundant in the intestinal lamina propria of normal rhesus macaques (Macaca mulatta).
Moreover, DP T cells have a memory phenotype and are capable of producing different
and/or higher levels of cytokines and chemokines in response to mitogen stimulation …
Abstract
Peripheral blood and intestinal CD4+CD8+ double‐positive (DP) T cells have been described in several species including humans, but their function and immunophenotypic characteristics are still not clearly understood. Here we demonstrate that DP T cells are abundant in the intestinal lamina propria of normal rhesus macaques (Macaca mulatta). Moreover, DP T cells have a memory phenotype and are capable of producing different and/or higher levels of cytokines and chemokines in response to mitogen stimulation compared to CD4+ single‐positive T cells. Intestinal DP T cells are also highly activated and have higher expression of CCR5, which makes them preferred targets for simian immunodeficiency virus/HIV infection. Increased levels of CD69, CD25 and HLA‐DR, and lower CD62L expression were found on intestinal DP T cells populations compared to CD4+ single‐positive T cells. Collectively, these findings demonstrate that intestinal and peripheral blood DP T cells are effector cells and may be important in regulating immune responses, which distinguishes them from the immature DP cells found in the thymus. Finally, these intestinal DP T cells may be important target cells for HIV infection and replication due to their activation, memory phenotype and high expression of CCR5.
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