Hyperactivation of platelets in asthma and introduction of platelet apheresis as treatment procedure.

Functional characteristics of platelets (Pts) were estimated in patients with different asthma forms (atopic and aspirin-sensitive). It was shown that Pts of asthmatics notwithstanding disease form are more sensitive to stimulating action of platelet-activating factor (PAF) in aggregation response and intracellular Ca2+ influx induction than Pts of healthy donors. Intracellular Ca2+ influx was measured using fluorescent zond Fura-2. Antiallergic drugs--ketotifen and sodium chromoglycate--caused 30-40% inhibition of PAF-induced aggregation of asthmatics' Pts. Platelet apheresis (PtA) was applicated attempting to normalize "hyperactivated" state of asthmatics' Pts. PtA treatment was performed using on-line cell separator Fenwal CS-3000 in 27 patients without any considerable side effect. Mean Pt yield was 400-600 X 10(9) cells; blood Pt count restored immediately after treatment. Positive clinical effect (complete reduction of asthmatic attacks for at least 2 months, improvement in respiratory function parameters) was observed in 19 out of 27 patients (70%). The clinical effect correlated well with the normalization of in vitro Pt response to PAF. It may be concluded that platelet apheresis has to be introduced as the treatment method for bronchial asthma, particularly in the patients with PAF-induced "hyperactivation" of Pts in vitro.