ALLERGIC BRONCHIAL-ASTHMA - EOSINOPHIL CHEMOTAXIS AND ANTIHISTAMINIC DRUG MODULATION

This paper investigated the chemotactic capacity of blood eosinophils (EOS) in response to C5a and formyl-leucyl-phenylalanine (FMLP) in 15 Parietaria-pollen-allergic patients with mild asthma during the Pariet aria pollen season. Data showed that EOS chemotaxis toward C5a was sig nificantly reduced during the peak pollen count, compared with the val ues obtained in normal subjects. On the other hand, FMLP could induce EOS chemotactic activity only in Parietaria-allergic patients, the hig hest value being registered during the height of the Parietaria season . In vitro cimetidine modulation of chemotactic function in comparison with C5a led to a recovery of the impaired results obtained in the pr esence of high histamine levels. Moreover, diphenhydramine preincubati on of EOS induced a reduction of the enhanced chemotactic activity obt ained with low concentrations. The data suggest that different serum h istamine levels give rise to an impaired immune-phlogistic response in allergic patients and that histamine-receptor antagonists may modulat e this effect.