Plasminogen activators in human nasal polyps and mucosa

Fibrinolysis is one of the processes that are involved in inflammation. In this study we have investigated if it is also involved in bilateral nasal polyposis, a disease with an inflammatory component. Fibrinolytic activity in the nasal mucosa and nasal polyps has been studied in 10 patients with bilateral nasal polyposis. Tissue-type plasminogen activator (t-PA) and urokinase-like plasminogen activator (u-PA) activities and antigen levels have been determined in polyp tissue and control nasal mucosa. t-PA activity is higher in nasal mucosa (median: 4.26 i.u./mg) as compared with nasal polyps (median: 0.65 i.u./mg; p = 0.03); u-PA activity is slightly lower in nasal mucosa (median: 0.040 i.u./mg) as compared to polyps (median: 0.065 i.u./mg; not significant). The percentage of u-PA to t-PA is 7.9% in nasal mucosa and 22.8% in nasal polyps (p < 0.01). The shift towards a higher u-PA/t-PA ratio in nasal polyps suggests an inflammatory process. Plasma levels of C-reactive protein are all within normal limits, which may suggest that PA activity is restricted to a local inflammatory reaction in the airway mucosa. The higher u-PA/t-PA ratio in nasal polyps and the higher levels of u-PA, when compared with the findings in other organs affected by inflammation, indicate that u-PA plays a part in the inflammatory events resulting in nasal polyps.