Oct. 27, 2003 Researchers at Columbus Children’s Research Institute (CCRI) on the campus of Columbus Children’s Hospital have identified a key component of protective immunity against the hepatitis C virus, the major cause of chronic liver disease and transplantation in the United States. The study found that successful control of hepatitis C infection required close cooperation between two types of white blood cells know as CD4+ “helper” and CD8+ “killer” T lymphocytes. The findings, published in the October 24 issue of Science, indicate that the immune system is unable to eliminate the virus without the CD4+ T lymphocytes.
“Our goal is to understand how a person’s immune response determines the outcome of the hepatitis C infection,” said Christopher M. Walker, Ph.D., director of the Center for Vaccines and Immunity at CCRI on the campus of Columbus Children's Hospital and professor of pediatrics at The Ohio State University College of Medicine and Public Health. “Approximately 70 percent of individuals exposed to hepatitis C become lifelong carriers of the virus. The remaining individuals successfully contain the infection and appear to have long-lasting immunity to the virus. Our finding that CD4+ T helper cells are essential for this protection move us one step closer to developing an effective vaccine for hepatitis C,” he added.
There are 170 million people around the world (including 4 million in the United States) infected with the hepatitis C virus. Most of these people don’t know they are chronic carriers of the virus until they develop liver problems.
The study, conducted in an animal model of human hepatitis C infection, demonstrated that temporary depletion of the CD4+ T helper cells abolished protective immunity against a second infection with the virus. The CD8+ T killer lymphocytes alone were an ineffective defense as the virus rapidly mutated to evade this immune response.
“Vaccines are the most cost-effective way to contain viruses like hepatitis C and with these findings, we move one step closer to that goal,” added Dr. Walker.
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