MAST-CELLS OF PSORIATIC AND ATOPIC-DERMATITIS SKIN ARE POSITIVE FOR TNF-ALPHA AND THEIR DEGRANULATION IS ASSOCIATED WITH EXPRESSION OF ICAM-1 IN THE EPIDERMIS
L. Ackermann et It. Harvima, MAST-CELLS OF PSORIATIC AND ATOPIC-DERMATITIS SKIN ARE POSITIVE FOR TNF-ALPHA AND THEIR DEGRANULATION IS ASSOCIATED WITH EXPRESSION OF ICAM-1 IN THE EPIDERMIS, Archives of dermatological research, 290(7), 1998, pp. 353-359
The release of cytokines from cutaneous cells may be of major importan
ce in the initiation and development of many inflammatory skin disorde
rs. For example, tumor necrosis factor-alpha (TNF-alpha), which in hea
lthy skin is found preformed only in mast cells, is able to induce the
expression of several adhesion molecules including intercellular adhe
sion molecule-1 (ICAM-1), Increased expression of ICAM-1 occurs in ker
atinocytes in lesional skin of psoriasis and atopic dermatitis (AD) an
d it is considered to be an important initiator of leucocyte/keratinoc
yte interactions in skin inflammation, We counted the mast cells showi
ng TNF-alpha immunoreactivity using a double-staining method in nonles
ional and lesional skin sections from 12 patients with AD and 12 patie
nts with psoriasis, The percentage of TNF-alpha(+) mast cells in lesio
nal and nonlesional AD skin was 36 +/- 22% and 21 +/- 15% (P < 0.018,
paired t-test), respectively, and in psoriatic skin was 16 +/- 25% and
15 +/- 15%, respectively (P < 0.89, paired t-test), We also cultured
whole skin biopsies taken from the healthy-looking skin of psoriatic a
nd AD patients in the presence of mast cell degranulator compound 48/8
0, which resulted in focal expression of ICAM-1 in the epidermis, In c
ultured keratinocytes, both histamine and an extract of a human mast-c
ell line (HMC-1) induced ICAM-1 immunostaining only in occasional cell
s, but the combination of histamine and the HMC-1 extract resulted in
intense ICAM-1 staining in numerous cells, This enhancement of ICAM-1
staining was abolished by preincubation of the HMC-1 extract with anti
-TNF-alpha antibody. These results suggest that the degranulation of m
ast cells induces the expression of ICAM-1 in keratinocytes probably v
ia TNF-alpha and histamine.