Acquisition of immune function during the development of the Langerhans cell network in neonatal mice

The immunological function of the Langerhans cell (LC) network in neonatal skin was examined by defining the development of cutaneous immunity relativ e to the structure, phenotype and function of the epidermal LC network in n eonatal, juvenile and adult mice. Analysis of epidermal sheets showed the p resence of major histocompatibility complex (MHC) II+, multilectin receptor DEC-205(-) cells within the epidermis of 3-day-old mice; both cell density and DEC-205 expression increased until day 14. When visualized with antibo dies directed at MHC II, the network was poorly formed in 3- and 7-day-old mice, as there was a lower cell density and poor MHC II expression on dendr itic processes, compared to mice at day 14. Application of a fluorescent an tigen to 3-day-old mice revealed that the LC were inefficient in transporti ng antigen to the draining lymph node. There was an improvement at day 7 an d by day 14 comparable numbers of antigen carrying cells were detected in t he lymph nodes of 6-week-old mice. The reduced antigen carriage in 3- and 7 -day-old mice correlated with a poor contact sensitivity response. This was not simply due to failure to present antigen, but development of immunosup pression, as transfer of T cells from adult mice that were previously treat ed with antigen when they were 3 days old, to adult recipients resulted in antigen specific immunosuppression. Analysis of CD80 and CD86 expression sh owed that LC from day 3 skin expressed CD80, but not CD86 and application o f antigen through this skin was inefficient in upregulating CD86. These fin dings indicate that when the neonatal LC network is poorly developed it is functionally immature and antigen applied through this 'functionally immatu re network' results in antigen specific immunosuppression.