The skin and the gut in psoriasis: the number of mast cells and CD3+ lymphocytes is increased in non-involved skin and correlated to the number of intraepithelial lymphocytes and mast cells in the duodenum
Michaëlsson G, Kraaz W, Hagforsen E, Pihl-Lundin I, Lööf L, Scheynius A
The aim of this work was to study tryptase+ mast cells and CD3+ T lymphocytes in non-involved skin in psoriasis and their possible relation to mast cells and lymphocytes in the duodenal mucosa. Skin biopsy specimens were obtained from 43 patients with psoriasis of variable severity and from 10 healthy subjects. Compared with the reference subjects, the number of mast cells in non-involved skin was clearly increased, most markedly in the papillary dermis. The increase was present both in mild, moderate and severe psoriasis. CD3+ lymphocytes were increased in non-involved skin in moderate and severe psoriasis. Patients with an increased number of duodenal intraepithelial lymphocytes had significantly more mast cells in non-involved skin than those without such an increase, and there was a significant correlation between the number of mast cells in non-involved skin and score for intraepithelial lymphocytes. However, when the 14 patients with increased intraepithelial duodenal lymphocytes were excluded-as they may represent a separate type of psoriasis-another type of correlation between the skin and the duodenal mucosa was found, namely a highly significant inverse correlation between the number of CD3+ lymphocytes in non-involved skin and the number of duodenal mast cells, which is highly elevated in psoriasis. The results might indicate an interplay between skin and intestinal mast cells and lymphocytes in a hitherto unknown way.