In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

One subtype of these cells are dysfunctional in IPEX syndrome, and one receptor on them is targeting by the OKT3 monoclonal antibody. Their development is aided by co-stimulatory CD28 signals, and they are activated following LAT phosphorylation by ZAP70. Their development is the subject of the Differential Avidity Hypothesis, and TSLP is responsible for activating the dendritic cells that educate them; that compound is secreted from Hassal's corpuscles. CD3 is present on their surface, and during development they interact with epithelial reticular cells to undergo rigid positive and negative selection against self-antigens, which ends with them either expressing CD8 or CD4 receptors. Coming in suppressor, cytotoxic, and macrophage-activated helper varieties, for 10 points, name this type of lymphocytes that matures in the thymus that are distinct from B cells.
Science