Other Talks in the Series: The Immune System - key concepts and questions

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My name is Brigitta Stockinger and I'm a group leader at The Francis Crick Institute in London. I'm going to talk about CD4 T cell subsets today.
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T cells are born in the thymus, which is an organ just above the heart. They undergo a series of differentiation steps in this organ and important checkpoints that ascertain they are functionally relevant. There are two types of T cells made in the thymus that are CD4 T cells, named such by the co-receptor CD4 on their surface, or a CD8 T cells named after a CD8 co-receptor. CD8 T cells are cytotoxic T cells that kill virus infected target. But today we're focusing on CD4 T cells, which are much more complex. They leave the thymus as mature CD4 T cells in two flavors they either have a regulatory phenotype. The abbreviation for that here is Treg or they are called T helper cells. When they enter lymphoid organs in the periphery, they experienced contact with antigen and contact with cytokines released from other cell type, and this shapes the further effector cell differentiation into the subset I listed here, classic Th1, Th2 later on, Th17, T follicular helper cells, and iTreg.