L. Brossay et al., ANTIGEN-PRESENTING FUNCTION OF MOUSE CD1 - ONE MOLECULE WITH 2 DIFFERENT KINDS OF ANTIGENIC LIGANDS, Immunological reviews, 163, 1998, pp. 139-150
Mouse CD1 (mCD1) is an antigen-presenting molecule that is constitutiv
ely expressed by most bone marrow-derived cells. Peptides with a hydro
phobic binding motif can bind to mCD1, and the peptide-CD1 complex is
recognized by CD8(+) cytolytic T cells. In contrast, NK1.1(+) T cells,
which are CD8(-), are autoreactive for mCD1 molecules. This autoreact
ivity, along with the ability of NK T cells to rapidly produce large a
mounts of cytokine, has led to the suggestion that these cells may be
immunoregulatory. We have shown that the mCD1-autoreactive T cells can
distinguish between different cell types that express similar levels
of mCD1, suggesting that mCD1-bound autologous ligands may be critical
for T-cell stimulation. Consistent with this, some of these mCD1-rest
ricted T cells can recognize the glycolipid alpha-galactosylceramide p
resented by mCD1, while others do not respond. The mCD1 crystal struct
ure reveals a deep and narrow hydrophobic antigen-binding site which c
an more easily bind lipid antigens than the long hydrophobic peptides
that we have defined as mCD1 antigens. The ability of mCD1 to bind and
present two different types of ligands raises the question as to how
mCD1 can accommodate both types of antigens.