Eat Right 4 Your Type brought attention to dietary lectins; some lectins or lectin containing substances have been used in medicine (traditional and conventional) for a variety of purposes, but primarily for their impact on the immune system. One of the largest uses of lectins by medical research is to convince certain immune cells to proliferate (a process called mitosis). It should be obvious that under some circumstances, this could be a huge health advantage. The other large use of lectins is as a probe or tool to identify cancer cells. This is the area where the Helix pomatia snail overlaps the gray area between food and medicine. Coincidentally, snail has a historic reputation as an anti-cancer food. So, lets look for a moment at what the research shows. This will be a bit technical, but I will use a metaphor at the end to attempt to illustrate the utility of this food.
Surface glycosylation (the expression of the glycoprotein (sugar/amino-sugar) antennae that project off of healthy cells such as the ABO antigens, or blood group MN antigens), which in normal cells is very precisely controlled, in cancer cells is often defective. This results in the elaboration of tremendous amounts of incomplete or altered glycoproteins, many of which (including tumor markers like CA-125, CA15-3, CA 19-9, T, and Tn) have clinical and diagnostic relevance. Before we get lost in terms like "surface glycosylation" or "glycoproteins", let's make sure we put this into a framework of something with which you might be a bit more familiar. In fact, in a sense you probably already are very intimately familiar with real world examples of these terms. "Surface glycosylation" simply means the fine architecture of antigenic structures that project off of your cells. The most readily recognized example of a "surface glycosylation" product is your blood type. "Glycoprotein", in a simple sense, means a molecule or chain made of protein-sugar (or amino sugar) and sugars. Again, your blood type antigen (A, B, O, or AB marker) is a real world example of a glycoprotein. So in effect, your blood type is an example of one "surface glycosylation" product and it is built from "glycoproteins".
Nature employs these specialized glycoprotein chains to create structures that act as carriers of biological information. The few monosaccharides (or simple sugars like galactose, mannose, fucose, etc.) and amino sugars (like glucosamine, N-acetylgalactosamine (terminal sugar on the A antigen), etc.) act almost like letters in an alphabet. Different combinations and lengths act to create a vocabulary of biological information. This biological information is then built onto the surface of your cells with things like your blood type. In effect this creates our cell's vocabulary and allows our cell's to communicate and interact with their environment.
On a healthy cell ABO antigens are clearly visible, but in diseased cells (like cancer cells), ABO antigens often disappear. Since your body has a disinclination to attack cells with your blood type marker, this disappearance of ABO antigens in cancer is a good strategy. So, the concept to understand is that cancer cells differ radically from their parental healthy cells in the fine architecture of their "cell surfaces". Again if we thought in simple terms, a healthy cell looks like a well maintained yard (bushes and trees). A cancerous cell would look like a field overgrown with grass after all of the bushes and trees have been cut down to barely visible stumps. This basically results from a cancer cell being unable to completely assemble a normal, healthy cell membrane structure like a blood type ABO antigen. In an ideal world, your immune system would be naturally predisposed to fight against cells with these incomplete or abnormal structures (just as it would against an invading virus).
Getting more technical again, in 1987 and 1991 Brooks and co-workers1, 2 reported that it is possible to predict lymph node involvement in women with breast cancer by the detection of altered surface glycosylation. Their 1991 study was performed on sections of 373 primary breast cancers, in a 24-year retrospective study. They found that the lectin, found in Helix pomatia, is extremely specific for attaching to or identifying cells with these improperly assembled (compared with a healthy cell) glycoproteins. So in effect, the less like a well-groomed yard, and the more like an overgrown field of grass a cell looks like, the more readily it can be identified by the lectin in Helix pomatia.
It appears that as breast cells become malignant and more prone to metastasis, their surface glycosylation products alter in a predictable manner, resulting in elaboration of markers characterized by the presence of a terminal sugar which can make the cell appear very A-like to your immune system.3 This can make the cell much more difficult for the immune system to recognize, especially for blood types A and AB. The key then is to capitalize somehow on these differences between healthy and cancerous. The lectin in Helix pomatia is one way to capitalize on these differences and interestingly, it would appear that the lectin in Helix pomatia becomes even more active as cell becomes more prone to metastasis.
Let's put this into a metaphorical picture to wrap up our discussion. Because cancer cells need to escape detection by your immune system in order to spread through your lymphatic system to distant parts of your body, anything that can be done to make cancer cells more visible to your immune system offers a potential advantage. Looking at this process in terms of a very generalized metaphor from Star Trek (I apologize to the non-Trekkies out their but this is a great visual example), cancer cells would be like a Klingon vessel trying to pass through federation space without being detected by the Enterprise or other federation starships. In the original series, the Klingon Empire, through their ingenuity, created a "cloaking device" which allowed them just such a means of escaping detection. In a sense, these altered glycosylation products on cancer cells may act very similar to the "cloaking device", allowing the cancer cells to travel through your space frontier (lymphatic system) without detection by your starships (your immune system). Continuing with this metaphor, in order to defeat the "cloaking device", crewmembers from the enterprise beamed aboard the Klingon vessel and stole the device, making the Klingon vessel now visible to their sensors. The lectin in Helix pomatia through its ability to recognize the altered glycosylation products on metastatic cells, appears to act in a similar way, turning off the cancer cells "cloaking device" and allowing it to be more visible to your immune system. As such, this food looks to be a good food to include in the diet, especially for A's and AB's.
References
1. Brooks SA. Lancet May 9, 1987: 1054-56
2. Brooks SA and Leathem AJC. Lancet, 8759, 338 (1991): 71-74
3. Springer G. J. Nat. Cancer Inst. 54,2 (1975):335-39
4. Schumacher DU. et al. Eur. J. Surgical Oncology; 22(6) 1996:618-620