Platelet-activating factor (PAF): a review of its role in asthma and clinical efficacy of PAF antagonists in the disease therapy.

PAF is a potent proinflammatory mediator which plays a role in different inflammatory diseases, including bronchial asthma. PAF is able to induce key pathogenic features of asthma and to influence the activity of cells involved in immune-inflammatory process; it may therefore serve as a possible direct target for anti-asthmatic drugs. Specific PAF antagonists (PAF receptors antagonists and recombinant plasma PAF acetylhydrolase attenuating its bioactivity) contributed to our better understanding of its role in asthma but unfortunately have not provided any further therapeutic option in the disease, due to minor or lacking effects. However, single treatment with PAF antagonist in asthma therapy revealed at its very best only a little effect. The concept of combined therapy targeting PAF and other mediators involved in the disease seems to be of particular interest. This review is a brief summary of relevant scientific basis as well as clinical research on the role of PAF in asthma, the significance of anti-PAF therapy in the disease, as well as US. patents (1998-2002) related to PAF antagonists.