J. Shutter et al., A DELTA-T-CELL RECEPTOR DELETING ELEMENT TRANSGENIC REPORTER CONSTRUCT IS REARRANGED IN ALPHA-BETA-T-CELLS BUT NOT GAMMA-DELTA-T-CELL LINEAGES, Molecular and cellular biology, 15(12), 1995, pp. 7022-7031
T cells can be divided into two groups on the basis of the expression
of either alpha beta or gamma delta T-cell receptors (TCRs), Because t
he TCR delta chain Locus lies within the larger TCR alpha chain locus,
control of the utilization of these two receptors is important in T-c
ell development, specifically for determination of T-cell type: rearra
ngement of the a locus results in deletion of the delta coding segment
s and commitment to the alpha beta lineage. In the developing thymus,
a relative site-specific recombination occurs by which the TCR delta c
hain gene segments are deleted. This deletion removes all D delta, J d
elta, and C delta genes and occurs on both alleles, This delta deletio
nal mechanism is evolutionarily conserved between mice and humans. Tra
nsgenic mice which contain the human delta deleting elements and as mu
ch internal TCR delta chain coding sequence as possible without allowi
ng the formation of a complete delta chain gene were developed, Severa
l transgenic lines showing recombinations between deleting elements wi
thin the transgene were developed. These lines demonstrate that utiliz
ation of the delta deleting elements occurs in cup T cells of the sple
en and thymus. These recombinations are rare in the gamma delta popula
tion, indicating that the machinery for utilization of delta deleting
elements is functional in alpha beta T cells but absent in gamma delta
T cells. Furthermore, a discrete population of early thymocytes conta
ining delta deleting element recombinations but not V alpha-to-J alpha
rearrangements has been identified. These data are consistent with a
model in which delta deletion contributes to the implementation of a s
ignal by which the TCR or chain locus is rearranged and expressed and
thus becomes an alpha beta T cell.