SPECIALIZATION OF MUCOSAL FOLLICULAR DENDRITIC CELLS REVEALED BY MUCOSAL ADDRESSIN-CELL ADHESION MOLECULE-1 DISPLAY

Follicular dendritic cells (FDC) in the mucosal lymphoid organs, Peyer 's patches (PP), display mucosal vascular addressin-cell adhesion mole cule-1 (MAdCAM-1). MAdCAM-1 decorates interlacing dendritic cells thro ughout PP follicles and is accentuated on FDC of the germinal center ( GC) light zone and on ''junctional'' dendritic-cells overlapping the B /T border and subepithelial dome region, sites associated with microen vironmental homing decisions, In contrast, MAdCAM-l is rarely displaye d by coronal or junctional FDC in peripheral lymph node follicles and is largely confined to the GC after lymph node immunization, FDC-assoc iated MAdCAM-1 plays a prominent role in lymphocyte adhesion to GC in PP frozen sections and participates significantly in binding to GC in chronically stimulated lymph nodes and spleen, but not to CC in lymph nodes after primary immunization (where binding is dominated by vascul ar cell adhesion molecule-1). Differential display of MAdCAM-l by FDC could contribute to the specialization of mucosal vs nonmucosal immune responses.