The purpose of this study is to determine if treatment with anti-IL-5 antibody has a prednisone-sparing effect in patients with symptomatic eosinophilic bronchitis (with or without asthma).

Eosinophilic bronchitis, which is identified by quantitative sputum cell counts (eosinophils greater than 2%) is responsive to corticosteroid treatment. It occurs alone or in association with asthma or in some patients with chronic obstructive pulmonary disease (COPD). In most patients the eosinophilic bronchitis responds to treatment with inhaled steroids but in some it requires a minimum dose of prednisone to keep it controlled. At present, there is no outstanding drug which can have a prednisone-sparing effect.

Interleukin (IL)-5 is a cytokine specifically focused on the development, differentiation, recruitment, activation and survival of the eosinophil. The specificity of IL-5 has raised the possibility that blocking it's activity, using humanized monoclonal antibodies, may be useful therapy for eosinophilic bronchitis. Such an antibody (SB-240563) has been introduced for clinical trial. The investigators will compare its effect versus placebo in patients with prednisone-dependant symptomatic eosinophilic bronchitis (with or without asthma) before and after a reduction in prednisone dose to identify if it has a prednisone-sparing effect.

The study is divided into 3 sequential study periods. Period 1: symptomatic eosinophilic bronchitis (with or without asthma) on the same dose of prednisone for 6-weeks or more. Period 2: standardized prednisone reduction (and inhaled steroid if prednisone is discontinued during the study treatment) at intervals of 4-weeks until there is a clinical and eosinophilic exacerbation or bothersome steroid withdrawl effects. Period 3: washout.

The patients will be seen every 2 weeks. Intravenous injections of SB-240563 750mg or placebo will be given at weeks 2,6,10,14 and 18. Doses of prednisone will be reduced in a standard way.

Inclusion Criteria:

1. Adult patients, aged 18-70 years, who have been followed as an outpatient and who have been found to require a minimum dose of prednisone treatment (in addition to high-dose inhaled steroid treatment) to prevent frequent exacerbations associated with induced sputum eosinophilia.
2. Patients will be enrolled if, at screening and baseline visits, they demonstrate sputum eosinophilia and symptoms. The symptoms may effect activity and sleep but should not, in the opinion of the treating physician, be severe enough to be of concern.
3. While FEV1 after withholding bronchodilators appropriately, before and after inhaled salbutamol (200 mg), and methacholine PC20 will be measured, these need not be abnormal since the prednisone is required for the control of eosinophilic bronchitis and any clinical consequences of this, and because the bronchitis can occur without these features of asthma.
4. On the same doses of corticosteroids for a least one-month.

Exclusion Criteria:

1. Pregnancy, breast-feeding or lack of effective contraception in females of childbearing potential or females who are postmenopausal <1 year.
2. Baseline FEV1 before bronchodilator of 40% or less of predicted. This lower FEV1 is acceptable since chronic airflow limitation secondary to the eosinophilic bronchitis or asthma is not an exclusion criteria. Neither is current or ex-cigarette smoking providing that the best FEV1 in these patients has been >60% predicted normal or the best FEV1/VC ratio has been >60% in the past two years.
3. Exposure to a relevant seasonal environmental allergen, known to worsen asthma control, during the study period.
4. Respiratory tract infection in the 4-weeks before the baseline visit.
5. Clinical exacerbation requiring extra prednisone treatment in the 4-weeks before V1.
6. Other cardiac, pulmonary, renal or systemic diseases that in the investigator's opinion may interfere with the study results or compromise subject's safety.
7. Previous participation in any study using anti-monoclonal drug.