Langerhans' cells in vitiligo.

To the Editor.— I have read with interest the article by Hatchome and colleagues, 1 confirming and extending the observation that elicitation reactions for contact sensitivity are diminished in vitiliginous skin. 1,2 I write to caution against two interpretations made from their data. The investigators pay considerable attention to differences in elicitation reactions to dinitrochlorobenzene, depending on whether immunization occurred through normal or vitiliginous skin. I note in Fig 2, left, that when immunization occurred through normal skin, elicitation reactions were significantly diminished in vitiliginous skin compared with normal skin. By contrast, when immunization occurred through vitiliginous skin, they observed no "statistically significant" difference in elicitation reactions. The investigators then employ this apparent contrast between two immunization sites as if it also were significant. In fact, the immunization site becomes an important part of their discussion, as noted in the first paragraph of their discussion. I believe this to be