Langerhans cells in human allergic contact dermatitis contain varying numbers of Birbeck granules. Double staining immunohistochemistry with OKT6 and Lag antibody.

Dynamic changes in human Langerhans cells (LCs) were studied with OKT6, anti-HLA-DR antibody, and Lag antibody in allergic contact dermatitis (ACD). Both T6-positive (T6+) cells and Lag-positive (Lag+) cells in the epidermis decreased in number from 0 to 48 h, but then gradually increased after day 7 of ACD. Lag+ cells after day 7 manifested a variety of staining intensities from weak to strong. It was also shown, after day 7, that some T6+ cells were Lag negative whereas all Lag+ cells were T6 positive. Flow cytometric analysis suggested that Lag-strongly-positive cells and Lag-weakly-positive cells belonged to the same population, and that the relative amount of Lag antigens in T6+ LCs gradually increased after day 7. Immunoelectron microscopy revealed that the Lag-strongly-positive cells contained numerous Lag-reactive Birbeck granules (BGs) whereas the Lag-weakly-positive cells contained fewer BGs in the cytoplasm. In some Lag-weakly-positive cells, no BGs were detected.