Specific localization of epidermal-type fatty acid binding protein in dendritic cells of splenic white pulp

Dendritic cells in the splenic white pulp of mice were intensely immunoreactive for epidermal-type fatty acid binding protein (E-FABP). This specific immunostaining revealed a clear difference in morphology between the dendritic cells in the periarterial lymphoid sheath (PALS) and follicular dendritic cells in the follicles in terms of cell sizes and process branching. No immunoreactivity was detected in dendritic cells in the marginal zones and the red pulp, although endothelial cells of almost all capillaries in the red pulp were immunoreactive for E-FABP. After peritoneal injection of lipopolysaccharide, the immunoreactive cells in PALS progressively enlarged and became rounded in shape with a peak in size at 24 h postinjection and they eventually resumed the dendritic form at 48 h postinjection. Within each of the enlarged immunoreactive cell perikarya were included small immunonegative apoptotic cells, presumptive lymphocytes. Taken together, E-FABP is useful as a marker for dendritic cells in the splenic white pulp, and may be involved through combination with fatty acids in antigen presentation and retention as well as in cytokine production.