BLOOD MARKERS OF EARLY AND LATE AIRWAY RESPONSES TO ALLERGEN IN ASTHMATIC SUBJECTS - RELATIONSHIP WITH FUNCTIONAL FINDINGS

We evaluated the relationship between blood markers of mast-cell (plas ma histamine and serum level of heat-stable neutrophil chemotactic act ivity [NCA]) and eosinophil (serum eosinophil cationic protein [ECP]) activation during early airway response (EAR) and late airway response (LAR) to allergen inhalation in 24 asthmatic subjects. After EAR, 14 subjects showed significant LAR (FEV(1) fall: greater than or equal to 25%), while 10 subjects showed equivocal LAR (FEV(1) fall: 15-20%). A significant increase from baseline value was observed in plasma hista mine and in serum NCA during both EAR and LAR, while serum ECP signifi cantly increased only during LAR. The sensitivity of different markers to detect significant FEV(1) fall during EAR and LAR was low, except for NCA. Changes in blood mediators were similar in both groups with s ignificant and equivocal LAR. There was a significant relationship bet ween the increase in NCA during EAR and the severity of LAR. Stepwise regression between changes in different blood markers showed a signifi cant relationship between histamine increase during EAR and ECP increa se during LAR. Thus, serum NCA is a more sensitive marker of EAR and L AR than plasma histamine and serum ECP, and its increase during EAR se ems predictive of the severity of the subsequent LAR.