Thursday December 2 7:20 PM ET
By Merritt McKinney
NEW YORK, Dec 02 (Reuters Health) -- Two genetic mutations can prevent the immune system from working properly, according to results of several new studies. While the illnesses caused by these genetic defects are rare, the findings may lead to a better understanding of diseases like multiple sclerosis and lupus, researchers say.
In one of three studies in the December 3rd issue of the journal Science, investigators report that children who have a rare, but fatal disease called familial hemophagocytic lymphohistiocytosis (FHL) have a genetic defect that prevents the production of a particular protein.
According to one of the study's authors, Dr. Vinay Kumar of the University of Texas Southwestern Medical Center at Dallas, it has been known that this protein, perforin, is used by immune-system cells to kill off infected cells. However, the new research shows that perforin also plays a role in regulating the immune system, Kumar told Reuters Health in an interview.
This means that the symptoms of FHL -- such as fever, blood and neurological irregularities and an enlarged spleen and liver -- occur when the immune system goes out of control, since it does not have perforin, according to Kumar.
While the discovery will not result in any new treatments for FHL in the near future, it may lead to a better understanding of illnesses like multiple sclerosis and lupus, known as autoimmune diseases, since they cause the body's immune system to react against its own tissues, Kumar said.
Two other studies in the same issue report on another genetic mutation that also impairs the immune system. The reports, one based on research in mice and the other on a person with an immune system disorder, both show that a defect in the gene that produces a protein called BLNK prevents the immune system from working properly. Without this protein, components of the immune system called B-cells do not mature.
When this happens, an individual cannot effectively fight infection, one of the investigators, Dr. Andrew C. Chan, of Washington University School of Medicine in St. Louis, Missouri, told Reuters Health.
Future research in mice will focus on developing gene therapy to restore the immune system when the BLNK gene is defective, according to Chan.
SOURCE: Science 1999;286:1949-1954, 1954-1957, 1957-1959.