Intravenous immunoglobulin (IVIG) replacement therapy is approved by the U.S. Food and Drug Administration to treat patients with compromised immune systems. The therapy also can be used to treat Lambert-Eaton myasthenic syndrome (LEMS). IVIG, available from many companies, is a protein mixture isolated from human blood.
How IVIG replacement therapy works
LEMS is a rare autoimmune disease in which the immune system mistakenly attacks an important protein found in nerve cell endings. This causes damage, which results in muscle weakness.
IVIG is a component prepared from human blood. Using donor blood, antibodies of a particular type — immunoglobulins — are isolated and purified of potential contaminants, such as other blood components. This mixture of antibodies is injected directly into the bloodstream of a LEMS patient.
The antibodies within the treatment are not targeted against the nerve cells. That means that the immune system cells which recognize antibodies are distracted from the autoantibodies against the body’s own tissues.
Treatment with IVIG also is thought to block the immune processes that are involved in targeting cells for destruction, competing with the autoantibodies and preventing them from acting on the nerve cells. In this way, the immune system is directed away from the nerve cells, reducing damage.
IVIG replacement therapy lingers in the blood for a few weeks before it is cleared and additional therapy is necessary.
IVIG replacement therapy in clinical trials
A number of small clinical trials were conducted in the 1990s which suggested that IVIG replacement therapy was effective in LEMS. These trials showed both an improvement in muscle strength, and a reduction in autoantibodies against the body’s own proteins.
A small crossover trial in nine LEMS patients treated with IVIG replacement therapy or placebo once a day for two days found significant improvement in measurements of muscle strength in the limbs and respiratory muscles. It also found a reduction in autoantibodies present in plasma. The results of the trial were published in the scientific journal Neurology. Improvements in muscle strength peaked at two-to-four weeks following treatment, and were diminishing by eight weeks after treatment.
Other information
IVIG replacement therapy is well-tolerated but can cause side effects, including headache, fever, chills, and fatigue. In rare cases, IVIG replacement therapy can cause kidney impairment, abnormal blood clotting, and transfusion reactions.
Last updated: July 24, 2019
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