How do T cells develop

How do T cells develop?

T-cell precursors from the bone marrow enter the thymus where they begin the process of becoming a naïve T cell. Nearly 99% of cells die in this process.

First, cells undergo positive selection in which the T cell must generate a TCR that, along with either CD4 or CD8, is capable of seeing antigen presented by MHC. The majority of circulating lymphocytes in the bloodstream are T cells with a TCR comprising an α-chain and a β-chain. To generate diversity, the TCR β-chain genes on chromosome 7 contain four segments (V, D, J, C), whereas the α-chain genes on chromosome 14 contain three segments (V, D, C). Each segment has several members to choose from (50-100V, 15D, 6-60 J, 1-2 C) in a process called gene recombination in which the T cell selects to use only one of each of these segments. This process of TCR gene rearrangement and the combination of the two TCR chains yield >10 8 possible combinations. After generating a TCR successfully, the T cell undergoes negative selection. In this case, T cells that bind too strongly to self-antigen or MHC and those that do not bind at all are eliminated.

T cells that survive the processes in the thymus are then released as naïve T cells into circulation where they will traffic to secondary lymphoid tissues to mature and differentiate.


Sign up to receive the trending updates and tons of Health Tips

Join SeekhealthZ and never miss the latest health information