I think the paper is so widely read and highly cited as it represented the first administration of a monoclonal antibody directed against interleukin-5 (IL-5) to man. Asthma is a disease characterized by an excess of eosinophils in the peripheral blood and lung tissue. IL-5 is critical to the maturation, recruitment and survival of eosinophils in blood and airways. Anti-IL-5 monoclonal antibodies had been used with some success in animal models of asthma, and there was great interest as to its effects in man. The rationale for the clinical trial was to determine whether anti-IL-5 could block peripheral and sputum eosinophil influx following inhaled allergen challenge, and whether this had any significant impact on airways hyper-reactivity as determined by response to inhaled histamine. The study was not designed to look at asthma symptoms.

The study provided an interesting, although by no means conclusive, result in terms of pathogenic mechanisms involved in asthma. Blood and sputum eosinophils were reduced significantly, but there was no significant effect on the physiological parameters measured, giving a hint that perhaps the eosinophil is not directly linked to lung function changes following inhaled allergen challenges. Further clinical trials are required to determine the effects of this drug on lung tissue eosinophils, and on symptoms and lung function parameters in patients with asthma.

Dr Maggie Leckie, MRCP, Ph.D.
Imperial College School of Medicine, Hammersmith Campus,
Department of Rheumatology, Hammersmith Hospital,
Du Cane Road,
London W 12 OHS