"The immune system may do two things: It may destroy your cancer, hopefully, and it may not destroy it," says Dr. Piotr Kraj, immunologist. "It's not known how the decision is made what to attack and what not to."

First glance is the best time to eliminate a cancer, says Dr. Kraj who hopes better understanding of how that does and doesn't happen will lead to new treatments utilizing the body's natural defenses. Funding from the Georgia Cancer Coalition's program for young investigators helped him develop the model. He recently received a five-year, $1.1 million grant from the National Cancer Institute to use the model to study prostate cancer and melanoma.

The work started with whittling the vast immune response to an examinable number of different T cells, which orchestrate the immune response, and expressing a known antigen in tumor cells that provokes the response.

The body has millions of T cells produced by the thymus, that start life nave, then develop a memory for thousands of antigens they encounter: everything from pollen to viruses to the body's own proteins and peptides. "Generally the mouse has a wide, abundant repertoire of T cell receptors," says Dr. Kraj. "If you take 10,000 T cells, there is a good chance each cell's is different.

"We wanted a system where we could look at a population of antigen-specific cells. The way we could do that is by making a transgenic mouse. The specificity of the T cells is biased to recognize one peptide and we know what that peptide is. We have a prostate cancer cell line that expresses this peptide. We can now move to the experiments where we can inject those mice with prostate tumor cells and see what happens," Dr. Kraj says. "We already are doing that with melanoma cells."

The usual first place antigens and T cells meet i
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Contact: Toni Baker
tbaker@mcg.edu
Medical College of Georgia
20-Apr-2005