Different cellular reaction patterns of epidermal Langerhans cells after application of contact sensitizing, toxic, and tolerogenic compounds. A comparative ultrastructural and morphometric time-course analysis.

BALB/c mice were treated with the irritants croton oil (0.5%, 20%), sodium lauryl sulfate (15%), and benzalkonium chloride (25%), the contact sensitizers 2,4-dinitrofluorobenzene (DNFB, 0.3%) and picryl chloride (PCl, 1%), and the tolerogen 2,4-dinitrothiocyanatebenzene (DNTB, 2%). All irritants used produced degenerative alterations of Langerhans cells (LCs). After application of 0.5% croton oil, however, this degeneration was preceded by an activation of the cells with increased number of mitochondria and enlargement of nuclei. The DNFB and PCl application in sensitizing doses to nonsensitized animals resulted in a cellular activation similar to that observed for 0.5% croton oil. In addition, these LCs showed enhanced adsorptive endocytosis as demonstrated by increased numbers of Birbeck granules and coated vesicles. The endocytotic activity was more pronounced in DNFB-sensitized animals. The DNTB at a concentration that induced tolerance to DNFB did not cause either cellular or endocytotic activation of LCs. These results demonstrate that the contact sensitizers DNFB and PCl induce characteristic cellular reaction patterns of LCs, which may be related to their sensitizing property.