CANCER CELLS ARE PROTECTED BY OUR OWN IMMUNE SYSTEM

Cancer Cells Are Protected By Our Own Immune System
In the early days of developing cancer, our immune system recognizes cancer cells as not to eliminate abnormal cells but as cells in our body to protect. These are the findings of research conducted in mice by a French team (1) (Paris, France). This work is published in the Journal of Clinical Investigation of August 3, 2009 (reference below).

"Immunosurveillance" Cancer
Scientists postulate since the early twentieth century that there is a "immunosurveillance" Cancer by which our immune system recognizes as abnormal cancer cells (2) once they are produced by our body can eliminate them. It is only when these cells escape the immune response that would develop cancer. But the team led by David Klatzmann, professor at UPMC, has just revealed that this concept is wrong: there is indeed a "Immunosurveillance" cancers that, in contrast, protects tumor cells at the time of their appearance are protected as any other normal cells of the body.

When immune response is activated by the body, two types of lymphocytes (specialized cells of the immune system) shall be put into play: the regulatory T cells and effector T cells. The first recognize the components from our own body and protects our tissues of an attack by the immune system. In contrast, effector T cells specifically recognize foreign components and serve to destroy them.

First days of the appearance of tumor cells
Most studies on interactions between cancer cells and immune system are made at advanced stage of cancer development, where the cancerous mass is already organized and detectable. The researchers were interested in these interactions, but in the early days of the appearance of tumor cells. They have shown in animal models that the appearance of the first cancer cells triggers an immediate response of regulatory T cells. These cells migrate rapidly to the tumor (3). They recognize the cancer cells of molecules that are also expressed by normal tissues of the body. These regulatory T cells while blocking the action of effector T cells, preventing them from attacking and destroying cancer cells. Permanently activated to protect our tissues, regulatory T cells are mobilized more quickly and strongly than are effector T cells that are resting them before the tumor appears. Researchers have also shown that in the absence of regulatory T cells during the first meeting between immune system and tumor cells, the effector responses of the immune system is put in place and can eradicate the tumor.

Regulatory T cells recognize the tumor, therefore the first and facilitate its development by preventing its elimination by effector T cells. This indicates that the control of regulatory T cells should be an essential component in the development of future therapies against cancer. This discovery also opens other therapeutic approaches such as vaccination preventive anti-tumor.

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Notes:
(1) This result was obtained by the team of Professor David Klatzmann Lab "Immunology - immunopathology - Immunotherapy (UPMC / CNRS / Inserm).

(2) A cancer cell (or tumor) is a normal cell of the body has undergone transformations such as uncontrolled proliferation, invasion of adjacent tissue, colonization of remote organs, genetic instability ...

(3) The term tumor refers, generically, an abnormal proliferation of cells. Malignancy, it is called cancer.

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Reference:
Article: Tumor emergence is sensed by self-specific memory CD44hi Tregs that create a dominant tolerogenic environment for tumors in mice
Authors: William Darrasse-Jezeera, Anne-Sophie Bergot, Aurelie Durgeau Fabienne Billiard, Benoit L. Salomon, Jose L. Cohen, Bertrand Bellier, Katrina Podsypanina et David Klatzmann
Journal Publication: Journal of Clinical Investigation

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Source: CNRS