Immunoglobulin or antibody replacement therapy is indicated for use in several conditions of antibody deficiency, a form of primary immunodeficiency that can cause chronic recurrent sinusitis, bronchitis and severe bacterial infections like pneumonia, deep-seated abscesses, osteomyelitis... It is a blood product taken from plasma pooling from about 10,000 - 50,000 healthy donors. Different products are supplied by different pharmaceutical companies that are slightly different but would work the same way of preventing infections. Your immunologist would choose one that is suitable for you. Replacement can be given either through monthly infusion which requires going to an infusion facility or subcutaneous route which can be done at home weekly, biweekly or monthly with a new formulary. For more information, please visit this topic at the Immune Deficiency Foundation.