To assess the safety of the administration of the drug (CAT-354) in healthy Japanese subjects.

The study design allows a gradual escalation of dose with safety monitoring to ensure the safety of the subjects.

Inclusion Criteria:

• Male or female subjects aged 20 through 55 years at the time of screening
• Signed and dated written informed consent is obtained prior to any study related procedure taking place
• No significant abnormality on clinical examination or medical history (excluding atopic skin signs, symptoms and history)
• A normal 12-lead electrocardiogram (ECG) (no clinically significant abnormalities)
• Clinical chemistry, hematology and urinalysis results within the laboratory reference ranges or deemed not clinically significant by the Investigator
• A negative screen for drugs of abuse and alcohol
• The following reproductive criteria apply:
• Females(of child bearing potential) must have a negative pregnancy test prior to the dose of investigational product and, unless surgically sterile (ie, bilateral tubal ligation, bilateral oophorectomy, or complete hysterectomy), has a sterile male partner, or at least 2 years postmenopausal, or practices abstinence; must use 2 effective methods of avoiding pregnancy (including oral, transdermal, or implanted hormonal contraceptives, intrauterine device, female condom with spermicide, diaphragm with spermicide, cervical cap with spermicide, or use of a condom with spermicide by the sexual partner) for 21 days prior to randomization, and must agree to continue using such precautions until 3 months after dosing with the investigational product; cessation of birth control after this point should be discussed with a responsible physician. A negative pregnancy test is required both at screening and prior to dosing.
• Males, unless surgically sterile, must use two effective methods of birth control with a female partner and must agree to continue using such contraceptive precautions from 21 days prior to randomization until 3 months after dosing with the investigational product.
• Japanese subjects. To be considered as 'Japanese', both of the subject's parents, and both sets of grandparents, must be Japanese. The subject must have been born in Japan, have a valid Japanese passport, and must not have lived outside Japan for more than 5 years.
• Body mass index (BMI) between 18 and 27 kg/m 2 , inclusive
• Able to comply with the requirements of the protocol

Exclusion Criteria:

• Any condition that, in the opinion of the investigator, would interfere with evaluation of the investigational product or interpretation of subject safety or study results
• Previously received monoclonal antibody, or a similar related protein, that might sensitize subjects to CAT-354 or to any component of the investigational product formulation
• History of an active infection within 4 weeks prior to screening, or evidence of clinically significant active infection, including ongoing chronic infection
• Any acute illness in the 14 days before Day 1 (Visit 2)
• Use of any medication (prescription or OTC) excluding hormonal contraception within 14 days (or 5-half lives, whichever is longer) of Day 1 dosing
• Involvement in another study of investigational medicinal product; within 2 months of the start of this study (Day 1) for small molecules, within 3 months of the start of this study for antibodies, or 5 half lives of the previously administered investigational product, whichever is the longer
• Any blood donation or significant loss of blood within 56 days of study initiation or plasma donation within 7 days of study initiation
• Subjects with immunodeficiency disorders
• Subjects who have a positive test for, or have been treated for hepatitis B, hepatitis C or human immunodeficiency virus (HIV)
• Any active concomitant disease including psychological disorders
• Subject is a participating Investigator, sub-Investigator, study coordinator, or employee of a participating Investigator, or is a first-degree relative of the aforementioned.
• Any factor which, in the opinion of the Investigator, would be associated with poor adherence to the protocol
• Female subjects: lactation