Differential expression of two distinct T-cell receptors during thymocyte development

Abstract

The product of the T-cell receptor (TCR) gamma-gene has recently been found to be expressed on a subset of both peripheral cells and thymocytes. As an initial approach to understanding the role of this gamma-chain of TCR (TCR gamma) in T-cell development, we have studied the ontogeny of TCR expression at the protein level in the developing murine thymus. We show here that the first T3-associated TCR to be expressed in the developing thymus is a disulphide-linked heterodimer composed of a gamma-chain of relative molecular mass 35,000 (Mr 35K) and a 45K partner (termed TCR delta). This TCR gamma delta is first detected approximately two days before the appearance of cell-surface TCR alpha beta heterodimers. We report that N-glycosidase digestions reveal that all of the gamma-protein expressed on fetal thymocytes, as in adult CD4-8-(L3T4-, Lyt2-) thymocytes, bear N-linked carbohydrate side chains. The major gamma-gene transcribed in mature, alpha beta-bearing T cells (V gamma 1.2C gamma 2)encodes no N-linked glycosylation site so these results suggest that the fetal gamma delta receptor defines a distinct T-cell lineage whose development in the thymus precedes classical alpha beta-bearing cells.

Development of the neonatal B and T cell repertoire in swine: implications for comparative and veterinary immunology

“…Similar to mice [86] and chickens [27], porcine γδ T cells are the earliest detectable T lymphocytes, developing first in the thymus at DG40 (Fig. 3C) and subsequently populating the periphery at DG45 (Figs.…”

Involvement of the interleukin 2 pathway in the rearrangement and expression of both alpha/beta and gamma/delta T cell receptor genes in human T cell precursors.

“…They code for two distinct types of heterodimeric TCR: the common MHC-restricted a/(3 heterodimer expressed on most functional T lymphocytes (14)(15)(16), and the recently described y/8 TCR complex, expressed on a minor T cell subset (17)(18)(19). Both structures are expressed in association with the monomorphic CD3 (T3) complex, but they seem to be acquired independently by distinct intrathymic subpopulations (20,21) .…”

Human T-cell antigen receptor (TCR) delta-chain locus and elements responsible for its deletion are within the TCR alpha-chain locus.

“…However, T cells appearing early in thymic ontogeny and dendritic epidermal cells display an alternative heterodimeric TCR, consisting of y and 8 chains, in association with the CD3 molecule (5)(6)(7)(8). Much is known about the genes encoding the a, P, and y chains, and their TCR products are derived from somatic recombination of variable (V), joining (J), and at times diversity (D) gene segments upstream of the constant-region (C) genes found in these loci (9).…”