The possibility of eliminating the class II antigen-expressing and antigen-presenting Langerhans cells from normal human epidermal cell suspensions was investigated. Cell suspensions containing 1.7-2.8% Langerhans cells were prepared by enzyme treatment of human skin obtained at plastic surgery. The cells were incubated with mouse monoclonal antibodies directed against the CD1 antigen present on Langerhans cells and were further incubated with magnetic particles, 4.5 micron in diameter, coated with sheep anti-mouse IgG. The optimal ratio between particles and target cells was found to be 40:1. The rosetted Langerhans cells were removed by a cobalt-samarium magnet. In six experiments immunoperoxidase staining revealed 0-0.1% (mean 0.03%) CD1-reactive Langerhans cells in the depleted cell fraction. The alloantigen presenting capacity of the depleted cell fraction, measured by [3H]thymidine incorporation, was abolished.