Dangerous Immune Response In Mice Pt. 3

Tracking Down The Cause: The Transgenic Protein In the GM peas?

From Spilling the Beans Newsletter, Nov/Dec 2005, by Jeffrey M. Smith, Author, Seeds of Deception

Previous:   1     2     Next:  4

What was it about the transgenic protein in the GM peas that caused it to affect the mice, when the 'same' protein in its natural form in kidney beans did not?

This question intrigued Hogan and his team. He said their 'scientific, inquisitive nature' led them to look for subtle differences in the protein structure. Although the amino acid sequences of the GM and non-GM proteins were identical, that doesn’t tell the whole story.

Amino acids are the building blocks, and according to Carman, “If you knock down a house and then study the pile of bricks, it won’t describe the house. Similarly, the amino acids don’t reveal the structure, shape and unique characteristics of the protein.”

David Schubert of The Salk Institute for Biological Studies points out that in higher organisms such as plants and animals, 'each cell type expresses a unique repertoire of enzymes capable of modifying protein structure.' Depending on where they are, a protein may have added molecular chains, 'such as phosphate, sulfate, sugars, or lipids,'[4] which alter their function. In a 2002 article in Nature Biotechnology, Schubert argues, “With our current state of knowledge, however, there is no way of predicting either the modifications or their biological effects.”[5]

We can, however, detect such modifications. For instance, when sugar chains are added to proteins, this process, known as glycosylation, can influence allergic responses. Hogan's team used the sensitive MALDI-TOF mass spectrometry technique, and confirmed that the GM and Non-GM proteins had slightly different glycosylation patterns. They believe that these subtle differences may be the cause of the immune responses.

Here again is more bad news. The MALDI-TOF method is not required and has rarely been used for the safety assessments of GM foods already on the market. According to Doug Gurian-Sherman, a senior scientist at the Center For Food Safety, and formerly at the Environmental Protection Agency, the difference in glycosylation between the GM pea protein, and the non-GM counterpart in kidney beans 'would not be detected by tests currently required by US regulatory agencies.' If companies do assess differences in protein, it is typically by 'gel' tests, which won't reveal the subtle differences in glycostation that may have caused the immune response. In fact, TJ Higgins looked at gel tests in the 1990's and didn't see any difference between the GM and Non GM proteins.

Approvals Rely on Dangerous Assumptions

Industry's assumption that proteins will act in a predictable manner in a new organism has been pivotal, and it certainly helped them get GM foods approved. Take, for example, their acute toxicity tests, where they feed rodents just the isolated protein. They don't necessarily extract the protein from the GM crop. Instead, they almost always produce the protein using genetically engineered bacteria, since it is cheaper and easier. They then test the animals' reaction to this surrogate protein, assuming that if animals don't react to the bacterial form, then they - and humans - won't react to the plant form.

These tests, therefore, avoid measuring the health impact of any changes in the protein in the crops we actually consume. The pea study revealed that significant, potentially deadly changes occurred when the gene for kidney beans is inserted into peas - closely related species. But the genes put into GM foods already on the market cross entire kingdoms. Bacterial genes are splice into GM soybeans, corn, cotton, and canola, and viral genes are inserted into papaya, zucchini, and crook neck squash. How these crops will alter bacterial proteins is anyone's guess - unfortunately.

Glycosylation is related to another problem. Proteins are sometimes folded in precise formations by specialized 'chaperone' folders inside the cell. If a novel protein appears in a species where it has never before existed, the chaperone folders might not do their jobs right. A mis-folded protein can be quite dangerous. In the case of the peas, the difference in glycosylation means that the protein is almost certainly a different shape, but there may be other shape-related issues that contributed to the immune reaction in mice.

In addition to changes in the target protein, side effects from the gene insertion process can create toxins, allergens or adjuvants. Earlier unpublished tests on the GM peas, for example, showed a doubling of trypsin inhibitor, a known allergen, and a fourfold increase in an anti-nutrient called a lectin. These or some other unknown change in the peas' composition might have played a part in increasing the immune responsiveness of the mice. In short, we don't really know why genetically engineered peas are more dangerous. We do know that the body interprets something in the pea as foreign, different, and offensive, and it reacts accordingly. On the other hand, all GM foods, by definition, have something foreign and different. It makes sense that the immune systems in humans or animals that have never eaten these novel substances before may react to them.

A handful of studies that have looked for immune responses have found them. In 1995, a Brazil nut gene inserted into soy DNA created an allergic reaction in human blood, and the project was stopped.[6] In 1998, a GM potato caused immune system damage in rats, among other problems.[7] Studies implicating the Bt-toxin have already been cited above. On top of those, a Bt potato caused abnormal and excessive cell growth in the small intestine of mice.[8] A feeding study with Bt corn called MON 863 caused a significant increase in male rats of three types of blood cells: basophils, lymphocytes (22%) and total white cell counts (20%).[9] This strongly suggests that consuming GM corn caused changes in the immune system. According to GM safety research expert Arpad Pusztai, 'A consistent feature of all the studies done, published or unpublished, including MON 863, indicates major problems with changes in the immune status of animals fed on various GM crops/foods, the latest example of this coming from the GM pea research in Australia.'[10]

We don’t have the advantage of sophisticated human clinical trials, so our evidence for immune reactions in humans is limited and preliminary. For example,

• Soy allergies jumped 50% in the UK just after GM soy was introduced[11]
• An expert panel in the US determined that there was a moderate likelihood that StarLink Bt corn contained a human allergen[12]
• Filipinos living next to Bt cornfields developed severe symptoms three years in a row—only while the corn was pollinating[13]
• A recent health report claims that Indian farm workers exposed to Bt cotton developed moderate or severe allergic reactions[14]

Certainly allergies and asthma are on the rise in many nations, but at this point, we can only guess whether GM food plays a part. The pea study provides a clue how it might be related.

Spilling the Beans is a monthly column available at Responsible Technology

Previous:  1     2      Next:   4

---

Articles and Reviews on Related Topics:

Congress Weakens Organic Standards Ecological Organic Agriculture EPA's Dirty Air Agreement Farmers Backs Against The Wall Over GMO Food Revolution Review Rat Babies Died - Mothers Ate GE Soy Got Local Organic Milk? Mad Cow Disease In The US Organic Consumers Association Seeds of Deception, Exposing Industry & Government Lies About GE Foods State of the Eco-Union, Joel Salatin

---

---

---

---