part of part of has plasma membrane part develops from immature alpha-beta T cell immature single positive thymocyte double-positive, alpha-beta thymocyte double-positive, alpha-beta immature T lymphocyte Double-positive (DP), alpha-beta thymocytes are a developmental stage in the production of mature alpha-beta T cells. These DP cells are found in the thymus. They are named 'double-positive' due to their expression of both CD4 and CD8 co-receptors on their surface, a characteristic that distinguishes them from other types of thymocytes. ‘Alpha-beta' refers to the type of T cell receptor (TCR) they express, differentiating them from gamma-delta T cells. In the preceding double negative (DN) phase, cells undergo an important developmental checkpoint called β-selection in which the β-chain of the TCR is rearranged and only cells expressing functional β-chains, combined with a surrogate α chain forming the pre-TCR, move forward in development. In the DP phase, cells downregulate expression of the surrogate α chain which is replaced by the α chain, which also undergoes gene rearrangements. This developmental stage is characterized by thymic selection processes that ultimately shape the T cell repertoire. Cells with nonfunctional TCRs undergo death by neglect, while cells expressing TCRs that bind strongly to self-peptides presented in the context of major histocompatibility complex (MHC) molecules are removed by negative selection, and cells that express TCRs that weakly interact with self-MHC are kept via positive selection. This ensures that the resulting mature T cells are able to recognize self-MHC without responding too strongly, which could result in autoimmune reactions. The CD4 and CD8 coreceptors play an important role in the selection processes, and the class of self-MHC that was recognized by the cell will dictate whether CD4 or CD8 expression remains on the cell while the other is downregulated. CD4 corresponds to the recognition of MHC class II while CD8 corresponds to MHC class I. The cell will then proceed into the single-positive (SP) phase and ultimately produce mature alpha-beta T cells. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) https://cdn.humanatlas.io/digital-objects/2d-ftu/thymus-thymus-lobule/v1.3/assets/2d-ftu-thymus-thymus-lobule.png DP thymocyte https://cellxgene.cziscience.com/cellguide/CL_0000809 A thymocyte expressing the alpha-beta T cell receptor complex as well as both the CD4 and CD8 coreceptors. Thymocytes of this stage are undergoing positive and negative selection. DP cell late cortical thymocyte thymocyte CD4 molecule T cell receptor co-receptor CD8 thymus