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THURSDAY, April 1 (HealthDayNews) -- Swiss researchers have created mice with human immune systems, making it possible to study diseases that attack humans without using people as subjects, a new report says.

Dr. Markus G. Manz, of the Institute for Research in Biomedicine in Bellinzona, and his colleagues took blood stem cells from human umbilical cords and transplanted them into infant mice that didn't have their own immune systems.

While earlier attempts failed to reconstruct the entire human immune system, this time the transplanted cells created many types of human immune system cells. These include cells called T-lymphocytes, B-lymphocytes and dendritic cells.

Moreover, Manz's group found these human immune cells worked along with the mouse's own cells to make lymph system organ structures -- a major component of the body's immune system -- and to produce regular immune responses.

The scientists report how they created these animals in the April 2 issue of Science.

"The model should provide a valuable tool to study pathogens that specifically target the human immune system and test potential therapeutic interventions," the researchers concluded.

Dr. Mike McCune, a senior investigator at the Gladstone Institute of Virology and Immunology at the University of California, San Francisco, said, "This modification of a humanized mouse clearly represents more than an incremental step over previously available animal models."

With further development, this small animal model could prove very useful in analyzing the human immune system, he added. This includes how the system develops, its function and its response to infectious agents such as Epstein-Barr virus and HIV.

"The model may even prove to be a useful one in which to study vaccines and therapies against such agents," McCune said. "The claims of the paper appear, if anything, to be understated."

Dr. Annie De Groot, an associate professor of community health at Brown University, noted that given this new mouse model, "effective vaccines for a whole range of pathogens, particularly those for which no animal model exists, might be developed in record time."

"The development of this mouse 'with a human immune system' is a giant step forward for vaccine development," she added.

While this new mouse model may not be perfect, "if it can be used to screen human vaccines it is a remarkable achievement," De Groot added.

More information

The National Institute of Allergy and Infectious Diseases has more on new vaccines and how the immune system works.

(SOURCES: Mike McCune, M.D., Ph.D., senior investigator, Gladstone Institute of Virology and Immunology, and professor, medicine, microbiology and immunology, University of California, San Francisco; Annie De Groot, M.D., associate professor, community health, Brown University, Providence, R.I.; April 2, 2004, Science)

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