Subsequent research suggests that this innate ability exists in the human immune system as well, although its effectiveness varies from person to person and from one time of year to another. Additional studies are being conducted to determine whether this immunity can be transferred from one patient to another.
Overview of the CR/SR Mouse Study
Occasional, though rare, cases of spontaneous regression in human cancers have been seen and documented in the past, but no satisfactory explanations for this phenomenon have ever been put forward.
While conducting a series of experiments with mouse sarcoma 180 (S180) cells, which form highly aggressive cancers in all normal mice, Dr. Cui and his colleagues happened upon a single mouse that surprised them with its ability to resist several forms of cancer, despite repeated injections of the sarcoma cells.
Breeding the mouse produced offspring that also exhibited cancer resistance, suggesting a likely genetic link.
The cancer-fighting trait appeared to decline as the mice aged; six-week-old mice appeared to resist the cancer completely when injected with S180 cells, while the older mice were more likely to first develop cancer and only thereafter experience spontaneous regression. Further experiments showed that in these cases it was a massive infiltration of white blood cells that destroyed cancer cells in these mice without damaging normal, healthy cells. [Click here to view video clips of the cellular activity associated with spontaneous regression.]
Based on these results, Drs. Cui and Willingham and their colleagues suggest that a previously unknown immune response may be responsible for spontaneous regression.
More recent studies, described in the May 8, 2006, Proceedings of the National Academy of Science USA, demonstrated the ability to cure cancer in normal mice by transferring purified immune cells from the cancer-resistant mice. These newer studies show that specific types of innate immune cells, such as macrophages, can migrate to the site of cancer in a normal mice and selectively kill all of the cancer cells without harming normal cells. Such studies suggest that this type of mechanism might one day be able to help design a new strategy for cancer therapy.