Primary immunodeficiency: types of immunoglobulin infusions

Immunoglobulin replacement therapy is one of the most commonly used treatments for primary immunodeficiency (PI). PI is an umbrella term for hundreds of genetic defects and disorders that disrupt how the immune system works. A person treating PI with immunoglobulin replacement therapy will receive regular infusions of a fluid that contains large amounts of proteins called antibodies.

How does immunoglobulin replacement therapy treat PI?

Immunoglobulins, or antibodies, are proteins that attach to harmful and/or foreign substances that enter the body (which are called antigens). Antibodies mark antigens as something that the immune system needs to destroy or remove. Examples of antigens include viruses, disease-causing bacteria, parasites, and chemicals. Antigens can also mark cells that are damaged or diseased, such as cells that are infected with a virus.

Different types of PI affect the immune system in different ways, but many types of PI cause problems with the immune system’s ability to produce antibodies. A person may not have enough antibodies or have antibodies that do not function normally. As a result, they will be more susceptible to infections (and more susceptible to serious infections). Other symptoms and complications can include an enlarged spleen, digestive issues, and autoimmune diseases.

Regular infusions of immunoglobulin replacement help the immune system function and help the body fight infections. The antibodies contained in an infusion are collected from blood donors.

How are immunoglobulin replacement infusions administered?

Immunoglobulin replacement therapy can be delivered with two types of infusions—intravenous infusions and subcutaneous infusions.

Here are some points to know about each option.

Intravenous immunoglobulin

• Intravenous means “into a vein,” and intravenous immunoglobulin (IVIg) is administered with a needle that is inserted into a vein.
• This type of infusion is given at a healthcare provider’s office or a hospital. Less commonly, it can be given at home by a home health nurse.
• Infusions are given every 3 or 4 weeks, though the exact schedule will be determined by a healthcare provider.
• A typical infusion can take between 3 and 4 hours.

Subcutaneous immunoglobulin

• Subcutaneous means “under the skin,” and subcutaneous immunoglobulin (SCIg) is administered with a needle that is inserted into a layer of fatty tissue under the skin. This is typically done in the abdomen, thighs, or upper arms.
• There are two types of SCIg, conventional and facilitated. Facilitated SCIg contains an additional medication that allows for a larger dose of immunoglobulin to be administered at one time.
• With training from a healthcare provider, conventional SCIg can be self-administered at home, or administered by a caregiver. The schedule can range from daily infusions to one infusion every two weeks., with the exact schedule determined by a healthcare provider. Infusion times vary depending on the dosage and the frequency of dosing.
• Facilitated SCIg can be administered at home or at a healthcare provider’s office. Infusions take 3 to 4 hours, and can be given every two, three, or four weeks. The exact schedule will be determined by a healthcare provider.

Some people may find treatment with SCIg easier to adhere to, because it involves fewer healthcare appointments and can be administered at home. Conventional SCIg allows for a constant state of immunoglobulin levels with little or no variation, compared to larger, less frequent dosages. Side effects such as chills, nausea, and aches are more common with IVIg and facilitated SCIg, which sometimes require pre-medication before infusions to prevent side effects.

But it’s important to remember that there is no best treatment option for PI, only the treatment option that works best for a particular person living with PI.

All therapies for PI will need to be individualized to a person’s specific diagnosis, symptoms, and needs. Your healthcare provider will be your best source of information.