ANTIGEN-BEARING LANGERHANS CELLS IN SKIN DRAINING LYMPH-NODES - PHENOTYPE AND KINETICS OF MIGRATION

Application of the fluorescent contact sensitizer Rhodamin B on mouse epidermis was used to study the migration kinetics of Langerhans cells into the draining lymph nodes. The expression of the dendritic cell m arkers NLDC-145 and MIDC-8 was followed over time to determine the cor relation between these markers and Langerhans cell migration. In contr ast with its high expression on intraepidermal Langerhans cells, the e xpression of NLD C-145 on dendritic cells in the draining lymph node w as low at 24 h but increased at later times; in contrast, MIDC-8 expre ssion on dendritic cells decreased. Ten days after Rhodamin B applicat ion, antigen-bearing Langerhans cells were still present in the epider mis; application of another unrelated contact sensitizer to the epider mis at this time did not lead to migration of these residual Langerhan s cells. These results indicate that not all antigen-bearing Langerhan s cells migrate from the skin after application of a contact sensitize r, indicating that signals in addition to simple antigen binding are n ecessary for migration. During this migration from epidermis to lymph nodes Langerhans eels undergo phenotypic changes. The decreased expres sion of the endosomal antigens MIDC-8 and MOMA-2 correlates with diffe rentiation from predominantly antigen-processing cells to predominantl y antigen-presenting cells. The reduced expression of NLDC-145 is disc ussed in light of a Langerhans cell-independent pathway of antigen tra nsportation from skin to lymph node.