INCREASED PLASMA-LEVEL OF PLATELET-ACTIVATING-FACTOR (PAF) AND DECREASED SERUM PAF ACETYLHYDROLASE (PAFAH) ACTIVITY IN ADULTS WITH BRONCHIAL-ASTHMA

We evaluated the plasma level of platelet-activating factor (PAF), a c hemical mediator that induces various symptoms of bronchial asthma, an d the activity of serum PAF acetylhydrolase (PAFAH), an enzyme that sp ecifically inactivates PAF, in adults with bronchial asthma. Measureme nts were made by radioimmunoassay of samples obtained from 137 adult a sthmatic patients (137 cases examined in remission and from among thes e 41 cases were also measured al the time of an asthmatic attack), 59 adult patients with untreated pulmonary tuberculosis and 106 healthy a dult volunteers. It was demonstrated that the plasma PAF le vel was ma rkedly higher and the serum PAFAH activity markedly lower in the asthm atic patients, both in remission and at the time of asthmatic attack, than in the healthy volunteers. The plasma PAF level was more closely associated with asthma both in remission and at the time of asthmatic attack than with pulmonary tuberculosis, whereas there was no signific ant difference in the serum PAFAH activity between the two diseases. T he low serum PAFAH activity in the asthmatic patients may have been du e to saturation as a result of continuous reaction to the increased pl asma PAF level in those patients.