A Study for GSK3862995B in Healthy Participants and Participants With Chronic Obstructive Pulmonary Disease

Prior treatment

• A history of recurrent infections, or treatment of a chronic infection within 3 months prior to the first dose of study drug, including both serious local infection (for example, cellulitis, abscess) or systemic infection (for example, pneumonia, tuberculosis, hepatitis B, shingles).

Other illness

• Participant has a past or current medical condition(s) or disease(s) that is/are not well controlled and, which in the judgement of the Investigator, may affect participant safety or affect study endpoints.
• Significant allergies to humanized monoclonal antibodies.
• Clinically significant multiple or severe drug allergies, intolerance to topical corticosteroids, or severe post-treatment hypersensitivity reactions (including, but not limited to, erythema multiforme major, linear immunoglobulin A (IgA) dermatosis, toxic epidermal necrolysis, and exfoliative dermatitis).
• Lymphoma, leukemia, or any malignancy within the past 5 years except for basal cell or squamous epithelial carcinomas of the skin that have been resected with no evidence of metastatic disease for 3 years.
• Breast cancer within the past 10 years
• Current or chronic history of liver disease or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones).

Lab values

• Alanine transaminase (ALT) \>1x upper limit of normal (ULN)
• Total bilirubin \>1.5xULN (isolated total bilirubin \>1.5xULN is acceptable if total bilirubin is fractionated and direct bilirubin less than (\<) 35%).

Other

• A clinically significant abnormality in 12-lead ECG readings performed at screening
• A clinically significant abnormality in the Holter monitor performed at screening (IV cohorts only).

• Healthy participants (Part A)
• Participant must be 18 to 65 years of age inclusive.
• Participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, and cardiac monitoring
• Body weight within the range 50-110 kilogram (kg) (inclusive)
• Body mass index (BMI) within the range 19.5-32 kilogram per square meter (kg/m\^2)
• Male and/or female of non-childbearing potential
  • Participants with Chronic Obstructive Pulmonary Disorder (COPD) (Part B)
• Participant must be 40 to 75 years of age inclusive.
• Body weight within the range 50-110 kg (inclusive)
• BMI within the range 19.5-32 kg/m\^2
• Participant has a confirmed diagnosis of COPD for greater than (\>)12 months
• Participants must present with a measured post-salbutamol Forced expiratory volume in 1 second/Forced vital capacity (FEV1/FVC) ratio of less than (\<) 0.70 at screening to confirm the diagnosis of COPD and a measured post-salbutamol FEV1 greater than or equal to (\>=) 40% of predicted normal values.
• Participants must have a well-documented requirement for optimized standard of care background therapy that includes daily inhaled medication.
• A peripheral blood eosinophil count of \>=150 cells/microliter (mcL) at screening
• Former cigarette smokers with a history of cigarette smoking of \>=10 pack-years at screening current smokers (includes the use of any type of nicotine containing product), or non-smokers are permitted
• Male and/or female of non-childbearing potential.