RECOMBINANT INTERLEUKIN-5 INDUCES INVIVO AIRWAY HYPERRESPONSIVENESS TO HISTAMINE IN GUINEA-PIGS

Interleukin-5-producing CV-1 cells were encapsulated in alginate and i njected i.p. in guinea pigs (4 x 10(6)/animal). These cells produced a pproximately 8 ng interleukin-5 per 4 x 10(6) cells per day. Airway hy perresponsiveness to histamine in vivo was observed 3 and 7 days after administration. The increase in lung resistance after intravenous adm inistration of histamine to guinea pigs was significantly potentiated, by approximately 70 to 90% in interleukin-5-treated animals. In anima ls treated with antibody to interleukin-5, the administration of inter leukin-5-producing CV-1 cells did not induce hyperresponsiveness. The percentage of eosinophils in broncho-alveolar lavage fluid was increas ed by 100% at 7 days but not at 3 days after administration of interle ukin-5-producing CV-1 cells. Antibody to interleukin-5 prevented the b roncho-alveolar lavage eosinophilia at 7 days after interleukin-5 admi nistration. It can be concluded that interleukin-5 induces broncho-alv eolar lavage eosinophilia and airway hyperresponsiveness and that thes e phenomena do not occur simultaneously. These data suggest a role for interleukin-5 in the development of airway hyperresponsiveness in bro nchial asthma.