[Leukotrienes. A review of the significance for disease in man and the possibilities for therapeutic intervention].

The leukotrienes constitute a group of 5-lipoxygenase catalyzed metabolites of arachidonic acid, the cellular effects of which may be divided into two broad categories. Leukotriene B4 is predominantly a leukocyte stimulant, and has recently been observed to represent the inflammatory cell component of a mutual activation mechanism between inflammatory cells and the immune system. It is thus anticipated that LTB4 acts as an inflammatory mediator and immune regulator in a variety of immune-mediated disorders. The presence of LTB4 in inflamed tissues from patients with psoriasis, rheumatoid arthritis and chronic inflammatory bowel disease renders it probable that the novel class of 5-lipoxygenase inhibitors and LTB4 antagonists will be capable of influencing the clinical course of these diseases. The other main group is comprised of leukotrienes C4, D4 and E4, collectively known as slow reacting substance of anaphylaxis leukotrienes, and has been identified primarily in immediate hypersensitivity conditions, e.g. bronchial asthma in which the smooth muscle contractile and permeability increasing properties of SRS-A appears to contribute to the early bronchoconstrictor phase. Leukotriene D4, however, may also be involved in the late reaction mediated by inflammatory cells, since it has the ability to immobilize neutrophils attracted by LTB4 to the inflammatory focus. The ultimate elucidation of the importance of leukotrienes in different diseases awaits the outcome of clinical trials with the newly developed highly potent and specific 5-lipoxygenase inhibitors and leukotriene antagonists.