Purified CD4 T cells were stimulated in vitro with anti-CD3 plus anti-CD28 antibodies to activate them, and cultured for two days in the presence or absence of all-trans retinoic acid (RA). The T cells were then stained with antibodies to either a$\alpha$4:$\beta$7 integrin or for E/P-selectin ligand expression and analyzed by flow cytometry. The results are shown in the upper graph in Figure. In a second assay, the cells were tested for their ability to migrate in response to a panel of chemokines, and the percentages of migrated cells were measured, as shown in the lower graph. Note that these chemokines are ligands for the receptors as indicated in Figure. In the absence of infection or inflammation, where are naive T cells encountering RA, and based on these data, what effect will this have on their subsequent behavior?

Question

Quizplus · Accepted Answer

The Answer is In the absence of infection or inflammation, the encounter between migrating dendritic cells and naive T cells in mesenteric lymph nodes is the generation of antigen-specific FoxP3+ regulatory T cells that express the gut-homing molecules CCR9 and integrin

\alpha

4:

\beta

7. These 'primed' T_reg cells then leave the lymph node and return to the wall of the small intestine.
The expression of gut-homing molecules require that the dendritic cells produce retinoic acid, which is derived from the metabolism of dietary vitamin A through the action of retinal dehydrogenases. Retinoic acid is also produced by stromal cells in the mesenteric lymph node, further enhancing the effects of the migratory dendritic cells. Retinoic acid-producing dendritic cells are also found in Peyer's patches.

Purified CD4 T Cells Were Stimulated in Vitro with Anti-CD3 α\alphaα

Purified CD4 T Cells Were Stimulated in Vitro with Anti-CD3 $\alpha$