Changes with time in Langerhans cell number, ATPase reactivity and morphology in murine epidermis after exposure to...

Effects on Langerhans cells of a single 200 mJ/cm2 dose of 284-316 nm UVB were studied in the dorsal epidermis of CBA/H mice. ATPase-positive cells were counted using light microscopy and compared with numbers of cells containing Birbeck granules. In interfollicular epidermis from untreated mice 633 +/- 20 (mean +/- S.E., n = 30) ATPase-positive cells/mm2 were found. By 3 days after UVB treatment, the number of ATPase-positive cells decreased by 90%, whilst the Birbeck granule-containing cell population was only reduced by 40% and very few cells had ultrastructural damage, suggesting that many Langerhans cells lost ATPase marker but remained intact. 7 d after irradiation there were 50% more cells with Birbeck granules than in controls, but the number of cells bearing ATPase remained below normal. ATPase-positive cell numbers approached normal only after a further 2-3 weeks. Langerhans cell responses after UVB differed from those previously found after X-irradiation.