Development of CD8α/α and CD8α/β T cells in major histocompatibility complex class I-deficient mice

Peripheral CD8⁺ T cells mainly use CDSα/β, and their development is mainly dependent on the major histocompatibility complex (MHC) class I proteins K^b and D^b in H-2^b mice. In this report, we have shown that the development of CD8α/β TCR-α/β cells in lymphoid organs as well as in intestinal intraepithelial lymphocytes (iIELs) is dependent on the MHC class I K^b and D^b proteins. In contrast, TCR-α/β CD8α/α cells are found mainly in iIELs, and their numbers are unaffected in K^bD^b double knockout mice. Most of the TCR-γ/γ cells in the iIELs also bear CD8α/α, and they are also unaffected in K^bD^b -/- mice. In β2-microglobulin (β2m)-deficient mice, all of the TCR-α/β CD8α/α and CD8α/β T cells disappear, but TCR- γ/δ cells are unaffected by the absence of β2m.