Immune Globulin
Key Terms: Autoimmune disease, Epinephrine, Immunoglobulins, Intramuscular administration, Intravenous administration.
Definition
Immune globulin is a concentrated solution of antibodies, pooled from donated blood, which is sometimes given to cancer patients whose own immune systems are either not working or are suppressed as a side effect of treatment. Immune globulin can also be called gamma globulin; in the United States some of the brand names are Gamimune, Gammagard, Gammar-P, Iveegam, Polygam, Sandoglobulin, and Venoglobulin.
Purpose
A healthy human body produces proteins called antibodies that act to destroy microorganisms (bacteria and viruses) that invade the body. Some cancer patients, due to the illness itself or side effects of treatment, become depleted of these proteins and therefore susceptible to serious infections. Immune globulin is given to these patients to restore their body's immunity. The use of immune globulin in this way is also called passive immunization. For example, immune globulin is given to bone marrow transplant recipients to prevent the development of severe bacterial infections while their own immune systems are not functioning, and chronic lymphocytic leukemia patients (of the type whose antibody-producing cells are the malignant cells) are given immune globulin to prevent the recurrent infections these patients sometimes suffer. Use in this disorder also allows the use of aggressive chemotherapy that will destroy the patient's own cancerous antibody-producing cells.
Immune globulin is also used to treat other diseases such as Eaton-Lambert Syndrome, a rare neurological disorder that sometimes occurs in association with small cell lung cancer called Eaton-Lambert syndrome, an autoimmune disease in which a patient's own antibodies attack nerve cells. The use of immune globulin appears to cause the body to reduce its own production of antibody, thereby improving the neurological disorder.
Description
Immune globulin primarily consists of antibody proteins of the type called IgG or gamma, although the solution may contain small amounts of other antibody types as well as sugars, proteins, and salt.
It is produced by pooling donated blood from at least 1000 people who have been tested to be free of blood-borne diseases like HIV or hepatitis. The antibody proteins are then separated out of the whole blood, and the pH of the immune globulin solution is adjusted to match the normal pH of blood. The preparation is also treated to remove any contaminants, including infectious bacteria or viruses.
Recommended Dosage
The dose of immune globulin used varies with the specific problem that it is being used for. When immune gobulin is used in patients with Eaton-Lambert Syndrome, the effective dose is usually about 1 g/kg of body weight/day. (One gram equals 0.035274 ounce; one kilogram equals 2.2046 pounds.) When used to counteract immunodeficiency, the dose is designed to produce an antibody level that stays at an effective threshold over a period of time.
When immune globulin is given to bone marrow transplant recipients, it is usually begun at the time of the transplant and continued for 100 days thereafter, with the objective of maintaining the level of IgG in the patient's blood above 400 mg per deciliter. (A deciliter equals 3.38 fluid ounces.) In patients with chronic lymphocytic leukemia (B-cell type) the target threshold for antibodies in the patient's blood is usually about 600 mg/dL. Although the amount required to maintain these levels varies from patient to patient (because different patients metabolize the drug at different rates) a dose between 10 and 200 mg/kg of body weight, given every 3-4 weeks, is usually sufficient.
Immune globulin is usually given intravenously, although intramuscular shots are available.
Precautions
Some people may have experienced severe reactions, including allergy-type reactions, to other antibody preparations. Generally, these people should not be given intravenous immune globulin. Patients with deficiency of antibody IgA, specifically, should also avoid the use of immune globulin. People with a tendency to form blood clots, or those with kidney problems should also avoid the use of this product, especially if elderly. While many pregnant women have been treated with immune globulin for different problems that have occurred during their pregnancy, since the method of action and specific effects on the fetus are not completely understood, pregnant women should avoid the use of immune globlulin unless it is clearly necessary. Any patient who is given immune globulin should be watched carefully, and epinephrine should be kept available in case a severe allergic reaction is experienced. Immune globulin which was made to be given through intramuscular injection should never be administered intravenously.
Side Effects
Administration of intramuscular immune globulin may result in tenderness, swelling, and possibly hives at the site of the injection.
Intravenous immune globulin may cause more severe reactions related to rapid introduction into the blood system. Possible side effects include headache, backache, aching muscles, fever, low blood pressure, and chest pain. More commonly, fever accompanied by chills or nausea and vomiting may be experienced. If these side effects occur, they are usually related to the immune globulin being administered too rapidly. If the rate of infusion is reduced, or if the infusion is stopped temporarily, negative effects will generally disappear. Rare, but potentially serious, side effects observed have been kidney failure and aseptic meningitis.
Interactions
Use of immune globulin may reduce the effectiveness of vaccinations (for example, measles, mumps, and rubella) for a few months following the use of the immune globulin preparation. Patients who have been given immune globulin should notify their doctors before any vaccinations are given. In addition, in some situations patients may need to have antibody levels measured to determine whether or not they have had previous infection with a specific microorganism. Use of immune globulin can create the false impression of prior exposure to the organism due to the donated antibodies in their blood.
—Wendy Wippel, M.S.
