Cp. Glade et al., THE DYNAMICS OF THE RESPONSE OF NORMAL SKIN TO SINGLE AND MULTIPLE EPICUTANEOUS LEUKOTRIENE B-4 APPLICATIONS ANALYZED BY 3-COLOR FLOW-CYTOMETRY, Acta dermato-venereologica, 75(6), 1995, pp. 437-441
Leukotriene B-4 (LTB(4)) is a potent chemoattractant and a well-establ
ished stimulator of DNA-synthesis in keratinocytes. Previously, repeat
ed applications of LTB(4) have been reported to induce a topically def
ined tachyphylaxis with respect to the extravasation of polymorphonucl
ear neutrophils. The aim of the present study was to quantify epiderma
l proliferation (% basal keratinocytes in S- and G(2)M phase), epiderm
al keratinization (% keratin 10-positive keratinocytes) and the appear
ance of ''non-keratinocytes'' including melanocytes, Langerhans' cells
and infiltrate cells (% vimentin-positive cells) in order to further
elucidate the effect of chronic exposition of normal skin to LTB(4). U
sing three-colour flow cytometry, we could reconfirm that the response
to one single epicutaneous application of LTB(4) was characterized by
a marked increase of the percentage of basal keratinocytes in S- and
G(2)M phase, and a marked increase of non-keratinocytes. Repeated appl
ications of LTB(4) induced a moderate increase of the percentage of ce
lls in S- and G(2)M phase and a moderate increase of the percentage of
keratin 10-positive keratinocytes. Remarkably, the percentage of nonk
eratinocytes had decreased following repeated applications of LTB(4),
compared to unchallenged normal skin, The present study suggests that
chronic exposure of normal skin to LTB(4) induces changes which differ
markedly from the histological features of the chronic psoriatic lesi
on, Therefore, LTB(4) is unlikely to be responsible for the perpetuati
on of the psoriatic plaque.