Inclusion Criteria:

• diagnosed with stable, mild, allergic asthma;
• history of episodic wheeze and shortness of breath;
• sexually active women of childbearing potential must use contraceptive during the entire duration of study;
• willing and able to give informed consent;
• positive methacholine challenge;
• positive skin prick test to common aeroallergens;
• positive allergen-induced early and late phase bronchoconstrictor response
• FEV1 at least 70% of predicted value;
• PC20 at baseline that is within 1 doubling dose of that measured during screening

Exclusion:

• active bacterial infection;
• respiratory tract infection or worsening of asthma within 28 days
• use of inhaled or topical steroids within 28 days or use of systemic corticosteroids within 90 days;
• use of cromoglycate, nedocromil, leukotriene receptor antagonists and inhibitors of 5-lipoxygenase within 14 days;
• use of antihistamines, immunosuppressives, or any medications that interact with eculizumab;
• use of theophylline-containing agents (any type), long-acting beta 2-agonists (salmeterol, formoterol) or long-acting anticholinergics within 14 days;
• use of NSAIDs prior to spirometry;
• use of tobacco products currently or within the previous 12 months; or smoking history > 10 pack-years;
• lung disease other than mild allergic asthma;
• patients with LAR who have not been vaccinated against Neisseria meningitidis;
• hepatitis B or HIV infection;
• parasitic infection;
• participation in any other investigational drug trial;
• pregnant or breast feeding women, or intending to conceive during the course of trial;
• known hypersensitivity to the treatment drug or any of its excipients;
• history of illicit drug use or alcohol abuse within previous year;
• any clinically significant abnormality on screening lab test results;
• abnormal chest X-ray;
• chronic use of any other medication for treatment of allergic lung disease other than short-acting beta2-agonists or ipratropium bromide;
• any medical condition that might interfere with the subject's participation in the study or confound the assessment of the subject;
• unwilling or inability to comply with the study protocol for any reason.