Polymorphonuclear leukocyte 5-lipoxygenase activity in psoriasis

Leukotriene B₄ Receptors on Neutrophils in Patients with Psoriasis and Atopic Eczema

“…Our findings of normal LTB4 receptor af finity and density and normal 5-lipoxygen-ase activity [ 15] of PMNL do not support the hypothesis of an intrinsic defect in the eicosanoid metabolism of psoriatic PMNL. Still, however, agents interfering with LTB4 recep tors seem to be a promising therapeutic ap proach in psoriasis.…”

“…Our results, however, complement findings of normal chemotactic response of psoriatic PMNL to LTB4 [22,23], suggesting that the accumulation of PMNL in psoriatic skin may be the result of an excess of cutaneous chemoattractant, rather than reflecting the increased readiness of psoriatic PMNL to migrate towards a che motactic stimulus. Indeed, elevated cuta neous levels of the chemoattractant eicosanoids LTB4 and 12-HETE were identified in psoriasis and atopic eczema [1][2][3]24], In addition, enhanced 5-lipoxygenase activity was found in skin of psoriatic patients [25] although peripheral PMNL of these patients display normal 5-lipoxygenase activity [15]. Thus, it is likely that elevated cutaneous lev els of chemoattractant eicosanoids may play a role in the initiation of the inflammatory infiltrate in both dermatoses, and that eico sanoids released from infiltrating inflamma tory cells may contribute to the maintenance of the inflammatory infiltrate and the hyper proliferation observed in chronic inflamma tory skin diseases [7], On the other hand, the altered responsiveness of monocytes from patients with psoriasis and atopic eczema towards LTB4 as demonstrated by Czarnetzki [26] leaves open the question of possi ble abnormalities of LTB4 receptors on cell types other than PMNL.…”

“…Preparation o f PMNL PMNL were isolated as previously described [15]. Briefly, 40 ml of heparinized blood was centrifuged at 150 g for 15 min at room temperature.…”