Interleukin 4 and interferon-gamma expression of the dermal infiltrate in patients with erythroderma and mycosis fungoides. An immuno-histochemical study

Background: Erythroderma, or generalized erythema of the skin, may result f rom different causes. At present it is unclear whether the underlying patho -mechanisms that lead to erythroderma are identical or different depending on the original disease. The aim of this study was to investigate the derma l cytokine profile in different types of erythroderma and mycosis fungoides . Methods: Snap-frozen skin biopsy specimens from 33 patients with erythroder ma were studied. Thirteen had idiopathic erythroderma, 7 erythrodermic atop ic dermatitis, 5 Sezary syndrome and 8 had erythroderma from miscellaneous causes. We also studied 6 patients with mycosis fungoides (5 plaques and 1 tumor) and 5 healthy non-atopic volunteers. The biopsies were immunohistoch emically stained for interleukin 4 (IL-4) and interferon gamma (IFN-gamma). All positive cells for IL-4 and IFN-gamma in the dermis were counted and t he number of positive cells was calculated per mm(2) IL-4/IFN-gamma ratio w as calculated for each biopsy. Results: The patients with idiopathic erythroderma, atopic dermatitis and m iscellaneous erythroderma, all showed more IFN-gamma-positive cells than IL -4-positive cells in the dermis. The median IL-4-/IFN-gamma ratio for these three groups was 0.6, 0.9 and 0.45, respectively. These differences were n ot statistically significant. All patients with Sezary syndrome however, sh owed more IL-4-positive cells than IFN-gamma-positive cells. The median IL- 4/IFN-gamma ratio was 1.8, which is significantly higher than in the other groups (p<0.05). In mycosis fungoides roughly the same number of cells expr essed IL-4 and IFN-gamma. The median IL-4/IFN-gamma ratio was 1.0, which is significantly lower than in Sezary syndrome (p<0.05). Conclusions: The dermal infiltrate in patients with Sezary syndrome mainly shows a T-helper 2 (Th2) cytokine profile, this in contrast to T-helper 1 ( Th1) cytokine profile in benign reactive erythroderma. This indicates that although a relative uniform clinical picture of erythroderma is obvious, a different patho-mechanisms may be underlying.