Mast cells and T cells share common homing/adhesion receptors, which s
uggests that they have evolved to use similar trafficking pathways. Fu
rthermore, these cells have been shown to co-localize in the gastroint
estinal mucosa, and it is possible that they act in concert to achieve
an immune response. Here, Tracey Smith and John Weis discuss the impl
ications of this potential collaboration.