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

Peripheral CD8(+) T cells mainly use CD8 alpha/beta, 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 CD8 alpha/beta TCR-alpha/beta 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-alpha/beta CD8 alpha/alpha cells are found mainly in iIELs, and their numbers are unaffected in (KDb)-D-b double knockout mice. Most of the TCR-gamma/delta cells in the iIELs also bear CD8 alpha/alpha, and they are also unaffected in (KDb)-D-b -/- mice. In beta 2-microglobulin (beta 2m)-deficient mice, all of the TCR-alpha/beta CD8 alpha/alpha and CD8 alpha/beta T cells disappear, but TCR-gamma/delta cells are unaffected by the absence of beta 2m.