Characterization of antigen presenting cells and T-cells in progressing scabietic skin lesions.

Experimentally infested dogs expressed successful adaptive immunity and self-cured of scabies after previously having scabies that required treatment to cure. A biphasic increase and decrease of CD1a+ Langerhans cells (LCs) in the epidermis of hosts infested the first time (sensitized) and infested a second time (challenged) suggested that these cells were actively involved in the hosts' early immune response to scabies. In contrast, in the dermis CD1a+ cell densities during both infestations increased to a single peak that followed the first peak of these cells in the epidermis. In addition, there was an influx of T-lymphocytes (CD3 epsilon + cells) and CD11c+ cells into the dermis following the first peak of LCs in the epidermis. The influx of T-lymphocytes in the dermis coincided with the peak density of CD1a+ cells in the dermis and epidermis during the second infestation. In both the epidermis and dermis, MHC Class II+ cell density profiles were similar to that of CD1a during the first infestation and then exhibited single peaks during the second infestation. The increases in CD1a+, CD3 epsilon + (T-lymphocytes), CD11c+, and MHC Class II+ cell responses in the dermis occurred earlier and were more intense in the challenge infestation compared with the first infestation. These data indicate that T-lymphocytes (CD3 epsilon +), CD11c+, MHC Class II+, and CD1a+ cells in the dermis played a major role in the successful immune response to scabies mites.