The use of a suction blister apparatus has facilitated study of the immunologic capacity of human epidermal cells. We have been able to prepare purified populations of these cells after blister formation. Specifically, using the blister tops, we are able to enrich for epidermal Langerhans cells which are very potent stimulators in antigen presenting assays. Thus, this normal volunteer study provides an important source of fresh epidermal tissue from which we can study normal epidermal Langerhans cell function. In addition, we have recently used blister roofs in important experimental models of HIV-1 transmission. There is no other method available for assessing the biologic function of freshly isolated Langerhans cells without altering their milieu. It is a very safe and effective way to obtain human epidermal samples.