No abstract

The number and distribution of mast cells in non-lesional and lesional skin samples from 13 psoriatic patients were analyzed enzyme- and immunohistochemically. Mast cell tryptase was stained with the sensitive substrate Z-Gly-Pro-Arg-4-methoxy-2-naphthylamide, and chymase with Suc-Val-Pro-Phe-MNA and monoclonal B7 anti-chymase antibody. In addition, healthy-looking skin from 27 psoriatic patients was tape-stripped resulting in induction of the Köbner response in 9 patients. Sequential biopsies were taken before and after (7, 14 and 21 days) tape-stripping, and both tryptase and chymase were stained enzyme-histochemically. In non-lesional psoriatic skin, 70 +/- 24% (mean +/- SD) of the mast cells contained chymase enzyme activity, and 78 +/- 18% chymase immunoreactivity. About 10% of the chymase-immunoreactive cells lacked chymase activity. In lesional psoriatic skin, tryptase-positive cells were increased in number throughout the dermis but especially beneath the epidermis. Chymase immunoreactivity paralleled the tryptase activity, whereas chymase activity was strongly diminished both in terms of mast cell numbers and in staining intensity in the papillary dermis. The apparent inactivation of chymase may be due to the action of the chymase inhibitors, alpha 1-antitrypsin and alpha 1-antichymotrypsin, localized immunohistochemically in mast cells of lesional and non-lesional psoriatic skin. In the developing psoriatic lesion, mast cells displaying chymase activity were already 27-38% decreased in number in the upper dermis on day 7 after tape-stripping, along with the first clinical signs of psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Several reports have shown the presence of T-helper lymphocytes with Th2 characteristics in the skin lesions of atopic dermatitis (AD). However, Th2 cells themselves require an exogenous pulse of IL-4 to initiate their differentiation and synthesis of IL-4. As mast cells have recently been shown to contain IL-4, this finding prompted us to investigate IL-4 in mast cells of AD lesions, to determine if they might provide the IL-4 pulse needed by the Th2 cells. In this study, we measured IL-4 immunoreactivity in mast cells of non-lesional and lesional skin sections from 20 patients with AD. Ten patients with nummular eczema (NE) without any atopic features or background, and five healthy subjects, served as the control groups. Mast cells were first identified using an enzyme--histochemical staining method for tryptase. Subsequently, the sections were photographed, the tryptase stain was removed, and IL-4 was demonstrated with a polyclonal antibody. The sections were photographed again, and the percentage of IL-4 positive mast cells was calculated. The percentage of mast cells exhibiting IL-4 immunoreactivity in the upper dermis in lesional vs. non-lesional skin was 66 +/- 18% vs. 37 +/- 18% in AD (P < 0.0001, paired t-test), but only 46 +/- 19% vs. 31 +/- 22% in NE. In the skin of healthy controls, only 23 +/- 25% of the mast cells were positive for IL-4. In addition, a significant difference was found between lesional skin of AD vs. NE patients (P < 0.008, unpaired t-test).(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

No abstract