This is a multi-center, randomized, placebo-controlled, double blind clinical study to assess the efficacy and safety of two separate dose regimens of Alpha-1 MP versus placebo for 156 weeks (i.e., 3 years) using computed tomography (CT) of the lungs as the main measure of efficacy. The two Alpha-1 MP doses to be tested are 60 mg/kg and 120 mg/kg administered weekly by IV infusion for 156 weeks. The study consists of an optional pre-screening phase, Screening Phase, a 156-week Treatment Phase, and an End of Study Visit at Week 160.

Inclusion Criteria:

• Have a documented total alpha1-PI serum level < 11 µM.
• Have a diagnosis of congenital AATD with an allelic combination of ZZ, SZ, Z(null), (null)(null), S(null), or "at-risk" alleles.
• At the Screening (Week -3) Visit, have a post-bronchodilator forced expiratory volume in 1 second (FEV1) ≥ 30% and < 80% of predicted and FEV1/forced vital capacity (FVC) < 70% (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage II or III).
• Have a carbon monoxide diffusing capacity (DLCO) ≤ 60% of predicted (corrected for HgB) within the past 2 years OR evidence of pulmonary emphysema on CT scan within the past 2 years per the Investigator's judgment.
• Have clinical evidence of pulmonary emphysema per the Investigator's judgment.

Exclusion Criteria:

• Has received alpha1-PI augmentation therapy for more than 1 month within the six months prior to the Screening Visit.
• Has received alpha1-PI augmentation therapy within one month of the Screening Visit.
• Has had a chronic obstructive pulmonary disease (COPD) exacerbation within the 5 weeks prior to the Screening Visit or during the Screening Phase.
• Unable to physically (e.g., unable to fit inside the CT scanner) or mentally (e.g., claustrophobic) undergo a CT scan.
• History of lung or liver transplant.
• Any lung surgery during the past 2 years (excluding lung biopsy).
• On the waiting list for lung surgery, including lung transplant.
• Smoking during the past 12 months or a positive urine cotinine test at screening that is due to smoking. Maybe on Nicotine replacement, including vapor cigarettes.
• History of anaphylaxis or severe systemic response to any plasma-derived alpha1-PI preparation or other blood product(s).
• Use of systemic steroids above a stable dose equivalent to 5 mg/day prednisone (i.e., 10 mg every 2 days) within the 5 weeks prior to the Screening Visit (inhaled steroids are not considered systemic steroids) or during the Screening Phase.
• Use of systemic or aerosolized antibiotics for a COPD exacerbation within the 5 weeks prior to the Screening Visit or during the Screening Phase.
• Known selective or severe Immunoglobulin A (IgA) deficiency.