Sex differences in the densities of epidermal Langerhans cells of the mouse.

Cutaneous immune reactions are known to show sexual dimorphism. Langerhans cells (LCs) are bone marrow-derived immune cells in the epidermis and are essential to immune reactions in the skin. In the present research, a study was made of the differences in LC density of male and female mice. Epidermal sheets were separated from the skin of the glabrous part of hind limbs and ears of specific pathogen-free (SPF) mice by ethylenediaminetetraacetic acid (EDTA) treatment and stained for adenosine triphosphatase (ATPase) activity. The density of LCs of hind limb epidermis in male C57BL/6 (823 +/- 20/mm2) and BALB/c (1689 +/- 66/mm2) mice was significantly less than that in females (1363 +/- 52/mm2, p less than 0.001; 2249 +/- 105/mm2, p less than 0.001, respectively). Langerhans cell density in the ears of male C57BL/6 (465 +/- 24/mm2) mice was also significantly less than that in females (542 +/- 17/mm2, p less than 0.02). Although ovariectomy failed to bring about any change in the LC density of hind limb epidermis in female C57BL/6 mice, the LC density in male C57BL/6 mice increased significantly at 4 weeks following orchiectomy (sham operation, 564 +/- 27/mm2; castration, 1179 +/- 49/mm2, p less than 0.001). These results indicate that mouse epidermal LC density depends on sex, i.e., male mice have fewer LCs than female mice. The reduction in LC density in males may possibly be caused by the testis.