T. Arstila et al., Identical T cell clones are located within the mouse gut epithelium and lamina propria and circulate in the thoracic duct lymph, J EXP MED, 191(5), 2000, pp. 823-834
Murine gut intraepithelial (IEL) T cell receptor (TCR)-alpha/beta(+) lympho
cytes bearing CD8 alpha/beta or CD8 alpha/alpha coreceptors have been shown
previously to express different oligoclonal TCR beta chain repertoires in
the same mouse, in agreement with other evidence indicating that these two
populations belong to different ontogenic lineages, with only CD8 alpha/bet
a(+) IELs being fully thymus dependent. CD8 alpha/beta(+), but not CD8 alph
a/alpha(+), T lymphocytes are also present in the lamina propria. Here, we
show that CD8 alpha/beta(+) lymphocytes from the lamina propria and the epi
thelium are both oligoclonal, and that they share the same TCR-beta clonoty
pes in the same mouse, as is also the case for CD4(+) T cells. Furthermore,
identical T cell clones were detected among CD8 alpha/beta(+) IELs and CD8
alpha/beta(+) blasts circulating into the thoracic duct (TD) lymph of the
same mouse, whereas TD small lymphocytes are polyclonal. These findings mus
t be considered in light of previous observations showing that T blasts, bu
t not small T lymphocytes, circulating in the TD lymph have the capacity of
homing into the gut epithelium and lamina propria. These combined observat
ions have interesting implications for our understanding of the recirculati
on of gut thymus-dependent lymphocytes and their precursors, and of the eve
nts leading up to the selection of their restricted TCR repertoire.