An assessment of Langerhans cell quantification in tissue sections.

In this paper we look at the regional variation of Langerhans cell (LC) numbers in tissue sections between different sites in the same individual and identical sites in different individuals. We also looked at the reproducibility of identification of LC in tissue sections by their OKT6 reactivity. In this way we could assess the validity of comparative enumeration in random tissue sections. Stepped sections were obtained and stained by the OKT6 method. The slides were projected, the cells counted, and an image analysis system used to measure the length of basement membrane. In this way we could calculate the number of LC per millimeter of basement membrane. Our subjects were six age- and sex-matched volunteers. We found that the number of LC on the trunk was significantly lower than on any of the limbs. However, each individual had significant site variation of LC that was different for each one. This makes direct comparison of individual sections invalid and suggests that the most suitable control, when counting LC in lesional skin, is adjacent normal skin.