Plant-based diets may be protective against multiple sclerosis because IGF-1 can prevent our immune system from eliminating autoimmune cells.
Clonal Deletion Theory of Immunity
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
How is it our immune system is able to distinguish between self and non-self? How does our immune system know what to attack, and what not to attack? As I described, the clonal selection theory of immunity suggests that we start out able to fend off basically every cellular structure in the known universe, because we have a billion different types of antibody-producing B cells—each capable of recognizing a different molecular signature.
Why, then, do we tend not to attack ourselves? It’s because before we’re even born, we kill off each and every B cell that recognizes us. It’s called clonal deletion; the killing off of forbidden clones. That’s what our thymus gland is for. When we’re still a fetus, our body lines up all our immune cells (our B cells, our T cells), holds up a picture of our self, and asks them, one by one: “do you recognize this person?” And if any of our immune cells say yes, they’re shot in the head. Killed on the spot; death by apopotosis, and good riddance.
Turns out this process of clonal deletion—ridding our bodies of self-recognizing immune cells—happens throughout our lives, mostly in our bone marrow. If you remember, though, as I talked about before, IGF-1, the cancer-promoting growth hormone boosted by animal protein consumption, prevents apoptosis, prevents our body’s killing of cells it wants to get rid of. That may be why IGF-1 levels are linked to cancer.
So, it is “of great interest to determine whether…[IGF may be contributing] to the inappropriate survival of lymphocytes in autoimmune or inflammatory conditions.” Maybe that’s why people who eat plant-based diets appear protected from autoimmune diseases—explaining, for example, the “extraordinary rarity of most autoimmune diseases among [for example] sub-Saharan rural blacks following a traditional vegan lifestyle.” Before they changed their diet, evidently not a single case of multiple sclerosis had been diagnosed among a population of 15 million.
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- Jennette JC, Falk RJ. The rise and fall of horror autotoxicus and forbidden clones. Kidney Int. 2010 Sep;78(6):533-5.
- McCarty MF. Upregulation of lymphocyte apoptosis as a strategy for preventing and treating autoimmune disorders: a role for whole-food vegan diets, fish oil and dopamine agonists. Med Hypotheses. 2001 Aug;57(2):258-75.
- Walsh PT, O'Connor R. The insulin-like growth factor-I receptor is regulated by CD28 and protects activated T cells from apoptosis. Eur J Immunol. 2000 Apr;30(4):1010-8.
- Venanzi ES, Benoist C, Mathis D.Good riddance: Thymocyte clonal deletion prevents autoimmunity. Curr Opin Immunol. 2004 Apr;16(2):197-202.
Images thanks to Shutterstock and Ilmari Karonen via Wikimedia
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
How is it our immune system is able to distinguish between self and non-self? How does our immune system know what to attack, and what not to attack? As I described, the clonal selection theory of immunity suggests that we start out able to fend off basically every cellular structure in the known universe, because we have a billion different types of antibody-producing B cells—each capable of recognizing a different molecular signature.
Why, then, do we tend not to attack ourselves? It’s because before we’re even born, we kill off each and every B cell that recognizes us. It’s called clonal deletion; the killing off of forbidden clones. That’s what our thymus gland is for. When we’re still a fetus, our body lines up all our immune cells (our B cells, our T cells), holds up a picture of our self, and asks them, one by one: “do you recognize this person?” And if any of our immune cells say yes, they’re shot in the head. Killed on the spot; death by apopotosis, and good riddance.
Turns out this process of clonal deletion—ridding our bodies of self-recognizing immune cells—happens throughout our lives, mostly in our bone marrow. If you remember, though, as I talked about before, IGF-1, the cancer-promoting growth hormone boosted by animal protein consumption, prevents apoptosis, prevents our body’s killing of cells it wants to get rid of. That may be why IGF-1 levels are linked to cancer.
So, it is “of great interest to determine whether…[IGF may be contributing] to the inappropriate survival of lymphocytes in autoimmune or inflammatory conditions.” Maybe that’s why people who eat plant-based diets appear protected from autoimmune diseases—explaining, for example, the “extraordinary rarity of most autoimmune diseases among [for example] sub-Saharan rural blacks following a traditional vegan lifestyle.” Before they changed their diet, evidently not a single case of multiple sclerosis had been diagnosed among a population of 15 million.
Please consider volunteering to help out on the site.
- Jennette JC, Falk RJ. The rise and fall of horror autotoxicus and forbidden clones. Kidney Int. 2010 Sep;78(6):533-5.
- McCarty MF. Upregulation of lymphocyte apoptosis as a strategy for preventing and treating autoimmune disorders: a role for whole-food vegan diets, fish oil and dopamine agonists. Med Hypotheses. 2001 Aug;57(2):258-75.
- Walsh PT, O'Connor R. The insulin-like growth factor-I receptor is regulated by CD28 and protects activated T cells from apoptosis. Eur J Immunol. 2000 Apr;30(4):1010-8.
- Venanzi ES, Benoist C, Mathis D.Good riddance: Thymocyte clonal deletion prevents autoimmunity. Curr Opin Immunol. 2004 Apr;16(2):197-202.
Images thanks to Shutterstock and Ilmari Karonen via Wikimedia
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Title
Clonal Deletion Theory of Immunity
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
This is the third in a video series on understanding the autoimmune theory of cancer, outlined in Cancer as an Autoimmune Disease, and continued in Clonal Selection Theory of Immunity. To learn how dietary manipulation of IGF-1 may affect cancer risk, see The Answer to the Pritikin Puzzle and How Plant-Based to Lower IGF-1? IGF-1 also appears to affect prostate gland growth. See Some Prostates Are Larger than Others; Prostate vs. Plants; and Prostate vs. a Plant-Based Diet. Next, we’ll finally get to the star of this video series: The Inflammatory Meat Molecule Neu5Gc. Be sure not to miss it.
For more context, check out my associated blog post: Plant-Based Diets for Multiple Sclerosis.
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