Relative efficiency of human Langerhans' cells and blood derived dendritic cells as antigen-presenting cells.

T4 cells recognize antigens together with HLA class II molecules in the membrane of antigen-presenting cells (APC). The magnitude of the induced T cell response is in part dependent upon the APC's amount of MHC-class II molecules. Langerhans' dendritic cells (LC) express 50-100 times more HLA-DR molecules than monocytes (Mo) and blood derived dendritic cells (DC). We report here that LC are more efficient APC than DC from the same donor, indicating that the APC capacity of dendritic cells isolated from different organs is correlated to their expression of HLA class II gene products.