GM Maize Disturbs Immune System of Young and Old Mice
By Dr. Mae-Wan Ho
November 19, 2008
The Italian government's National Institute of Research on Food and Nutrition has just published a report online in the Journal of Agricultural Food Chemistry documenting significant disturbances in the immune system of young and old mice that have been fed the GM maize MON 810. This follows hot on the heels of results released by the Austrian government showing that GM Maize Reduces Fertility & Deregulates Genes in Mice (SiS 41). These revelations confirm a string of previous findings on adverse health impacts of GM food and feed, leave us in little doubt that GM is Dangerous and Futile (SiS 40). Proponents should stop misleading the public that GM food and feed is safe.
The GM maize and the parental non-GM variety from which it was derived, were grown simultaneously in neighbouring fields in Landriano, Italy, from seeds provided by Seeds Emporda (Girona, Spain). The control maize flour from the non-GM parental strain had a low level of GMO contamination (0.29 percent by PCR test) but only the GM maize had the specific gene coding for the toxin Cry1Ab that acts as a pesticide.
The GM and non-GM maize were also analysed for levels of the fungal aflatoxins B1, B2, G1, G2, fumonisin B1 (FB1), deoxynivalenol (DON), ochratoxin, and zeralenon, that frequently contaminate maize grains. The values were below the maximum allowed in Europe, except for FB1 (1350 and 2450 mg/kg) and DON (1300 and 650 mg/kg) in GM and non-GM maize respectively.
The diets were formulated according to accepted standards and contained 50 percent MON810 or its parental control maize flour. A standard pellet diet containing about 50 percent of commercial non GM maize was also used, which did not contain CrylAb by PCR test.
Weaning mice, 21 days old, were fed with the diets for 30 and 90 days, and the old mice, 18 to 19 months, were fed for 90 days on the test diets; and male Balb/c mice were used in all the experiments.
There were no differences in the mean body weight or in food consumed between the GM-fed and control mice. These are the 'agronomic' characteristics typically measured in feeding tests, and all too often, the only characteristics measured.
The total number of white blood cells in the small intestine, spleen and blood were not different. However, there were significant differences in the percentages of T and B cells, and of CD4+, CD8+, gdT+, and mbT+ subpopulations in both weaning and old mice that were GM-fed for 30 and 90 days respectively compared with controls. These changes appeared in the gut, spleen and blood, and were accompanied by increase in blood cytokines IL-6, IL-13, IL-12p70, and MIP-1b, all involved in allergic and inflammatory responses. These changes were not detected in the mice fed the commercial non-GM pellet diet.
The greatest effects were the weaning mice fed for 30 days on GM maize, whereas those fed for 90 days only had increased B cells. In the old mice, the induced changes were similar to those found for the weaning mice fed for 30 days. These results show that very young and old mice are more susceptible to immunological insults. By the time the mice were 111 days old (90+21), a degree of tolerance had been established, so that the disturbances were reduced.
The immune disturbances are significant also in view of findings from another laboratory; proteomic analysis identified 43 proteins that were up or down regulated in the MON 810 maize seeds compared with the parental strain, among them a 50 kda g-zein, a well-known allergenic protein, that was not present in the parental strain.
It is clear that genetic modification is inherently hazardous, as it invariably result in unpredictable and uncontrollable changes in the genome and the epigenome (pattern of gene expression) that impact on safety.
References available on request