Response of polymorphonuclear leukocytes to topical leukotriene B4 in healthy and psoriatic skin.

The in situ infiltration of polymorphonuclear leukocytes following the topical application of leukotriene B4 to the clinically uninvolved skin of psoriatic patients and the skin of normal controls has been quantified using elastase as a marker enzyme. The magnitude of this response in the psoriatic patients proved to be significantly diminished compared with the response in the controls. The time course of the response was similar in both groups, maximum elastase activity being seen about 18 h after application of the LTB4.