IN-VITRO AND IN-VIVO EFFECTS OF TACHYKININS ON IMMUNE CELL-FUNCTION IN GUINEA-PIG AIRWAYS

The effects of sensory neuropeptides substance P (SP) and neurokinin A (NKA) on immune cell recruitment and macrophage activation were deter mined. Guinea pigs exposed to capsaicin aerosol exhibited eosinophil a nd neutrophil influx into their bronchoalveolar lavage (BAL) fluid 24 h after treatment; SP aerosol elicited eosinophil influx, whereas NKA aerosol exposure caused neutrophil recruitment. Inhalation of capsaici n, NKA or SP aerosols also enhanced superoxide production induced by z ymosan in cultured alveolar macrophages. Incubation of alveolar macrop hages with SP or NKA in culture for the same time (24 h) did not poten tiate the response to zymosan. Hence, tachykinin-mediated airway effec ts may not be the result of direct actions on target cells but rather involve alternate mechanisms and mediators which do not necessarily re flect in vitro data.