title: Platelet-activating factor in late asthmatic response.
abstract: The role of platelet-activating factor (PAF) in the late asthmatic responses was studied. The concentrations of lyso-form of PAF in plasma were measured at 0 and 20 min, and 6 and 24 h after the antigen inhalation challenge among patients with bronchial asthma. PAF activities were measured by their aggregating ability of washed rabbit platelets after acetylation of lyso-PAF into the biological active form of PAF, when there were no detectable amounts of PAF in plasma. The concentrations of lyso-PAF were found to be significantly increased in patients with the late asthmatic response compared with patients with the single immediate response at 6 h after the antigen challenge. In contrast, lyso-PAF levels were not significantly different at 20 min after the antigen challenge between these two groups. PAF inactivator activity in plasma increased when there was a decrease in the lyso-PAF level. These results suggest that PAF may participate in the late asthmatic response and may provide a new insight into the pathogenesis and the treatment of bronchial asthma.
mesh_terms: D001249:Asthma / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology / Q000503:physiopathology; D008297:Male; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors / Q000502:physiology*; D010974:Platelet Aggregation; D013997:Time Factors
chemical_list: D010972:Platelet Activating Factor