Hello, I'm curious as to why cancer xenografts must occur in immunodeficient mice. Ordinarily would the mouse immune system eliminate the cancer cells? And why would this not occur in regular human patients with cancer from which the tissue originates? Thanks.
As others have explained, the immune system in a mouse would target the foreign cells, which is why nearly all xenografts (see a list here: http://altogenlabs.com/xenograft-models/) are conducted with immunodeficient mice. Other experiments nowadays have been conducted in mice with immune systems that mimic those of humans. The reasons why cancers in humans are not attacked are complicated - usually the cancers are attacked, and most of the time the immune system is successful at killing the cancer. However, sometimes the cancer cells escape the detection of the immune system, or the immune system itself is cancerous, and in such cases treatment is a lot more complicated.
When you make a xenograft you are using cells of another mouse or of another species. This will inmediately create an immune reaction of rejection. This is why you have to use immunoincompetent mice. But cancer from the same individual is not a "strange" tissue for that individual. There is no immediate rejection. In this case the mechanisms produced by the same tumor (ctla4, pd1, pdl1, etc.) are sufficient to block normal immunosurveillance.
The transplanted cells being from a different animal is a great point from Tomas Koltai, but I would add that in many cases initially the elimination of cancer cells does happen in "regular" humans. We tried to collect the reasons why some tumors may escape the immune control in Figure 2 of our recent publication (see attached), you might find it interesting.
Foreign or incompatible tissue or cell structure is etiological amounting to carcinogen theory. The study seems to be a point of discovery for what might be an etiology of sorts without the administrative point of manipulation (stimulus) being killed off by it's own antibodies. The xenografts are simply confirmation that through the duration of the experiment, the test sample is still within the specimen (mouse/mice). Trauma, radiation level on a micro point of calibration (hypothetical) {give or take} are all aspects of discovering biological morphism and the different hemostasis that can develop...
Michael S.
As others have explained, the immune system in a mouse would target the foreign cells, which is why nearly all xenografts (see a list here: http://altogenlabs.com/xenograft-models/) are conducted with immunodeficient mice. Other experiments nowadays have been conducted in mice with immune systems that mimic those of humans. The reasons why cancers in humans are not attacked are complicated - usually the cancers are attacked, and most of the time the immune system is successful at killing the cancer. However, sometimes the cancer cells escape the detection of the immune system, or the immune system itself is cancerous, and in such cases treatment is a lot more complicated.