Decreased CD11b expression on circulating polymorphonuclear leukocytes in patients with extensive plaque psoriasis

J.P.A. van Pelt; E.M.G.J. De Jong; P.E.J. van Erp; P.C.M. van de Kerkhof



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Decreased CD11b expression on circulating polymorphonuclear leukocytes in patients with extensive plaque psoriasis
European Journal of Dermatology. Volume 7, Number 5, 324-8, July - August 1997, Revues
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Author(s) : J.P.A. van Pelt, E.M.G.J. De Jong, P.E.J. van Erp, P.C.M. van de Kerkhof
Summary : In psoriasis, polymorphonuclear leukocytes are consistently present in the early psoriatic lesion and in actively spreading plaques. CD11b, which is part of the b2-integrin receptor Mac-1, plays an important role in various biological functions of the polymorphonuclear leucocyte such as leukocyte adhesion to endothelium, extravasation, tissue migration and degranulation. In the present study we investigated the possibility of systemic differences in leukocyte CD11b-expression between patients with extensive plaque psoriasis and healthy volunteers. Venous blood samples were obtained from 15 patients with extensive plaque psoriasis (Psoriasis Area and Severity Index greater than 10.0), and from 15, matched, healthy controls. Both unstimulated and in vitro leukotriene B4- stimulated leukocytes were stained for CD11b, which was quantified using flow cytometry methods. A tendency towards decreased basal CD11b expression was observed on leukocytes from psoriatic patients compared to healthy subjects. After in vitro stimulation with leukotriene B4 (LTB4), the difference between psoriasis patients and controls increased further and was statistically significant. Patients with unstable psoriasis (increasing size of individual lesions and/or pinpoint papules around chronic plaques) proved to have even lower unstimulated and LTB4-stimulated CD11b expression. No correlation was found between CD11b expression and severity of psoriasis using the PASI-score. Interestingly, the relative CD11b up-regulation (ratio CD11bLTB4-stimulated/CD11bunstimulated) was virtually the same in both groups. Therefore, the signalling pathway from leukotriene B4-receptor binding up to cd11b expression on the leukocyte surface, was essentially normal in psoriasis. It is hypothesised that the decreased CD11b expression in psoriasis patients is caused by leukocyte compartmentalisation.
Keywords : blood, CD11b, flow cytometry, leukotriene B4, polymorphonuclear leukocyte, psoriasis.