T lymphocytes of the immune system are vital to bodily defenses against viruses and cancer. T lymphocytes are activated in part by molecules called co-stimulatory signals, of which 4-1BB is one example. However, tumor cells are cleverly able to turn off the effects of some co-stimulatory molecules, thus ensuring their own survival.
Recent experiments in mice have shown that binding a monoclonal antibody to 4-1BB activates this co-stimulatory molecule and triggers a strong immune response. Based on this knowledge, Karl Erik Hellstrom and colleagues at the Pacific Northwest Research Institute in Seattle have developed a form of gene therapy to treat cancer (Nature Medicine, Vol. 8, No. 4, 01 Apr 02, p. 343). They inserted a gene for a fragment of the antibody to 4-1BB into mouse melanoma cells and used these ‘transfected’ cells to vaccinate other mice.
The inoculation stimulated the immune system against cancer cells and vaccinated mice were able to reject other tumors. Lieping Chen of the Mayo Clinic discusses the potential of this gene therapy vaccine to treat human cancers (p. 333).
Dr. Karl E. Hellström
Pacific Northwest Research Institute
Seattle, WA 98122
Tel: +1 206 726 8747
Fax: +1 206 860 6773
Dr. Lieping Chen
Department of Immunology
200 First St, SW
Rochester, MN 55905
Tel: +1 507 538 0013
Fax: +1 507 284 1637
Email Address: email@example.com
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