Friday, May 29, 2009

Cow's milk allergy & recombinant proteins

A quick post about stuff I don't understand:
A friend of mine has an infant that is allergic to cow's milk. This is common and, who cares, since the infant is being breast fed. EXCEPT for the fact that the infant is allergic to the dairy products that the mother is consuming. This is somewhat uncommon but certainly not unheard of. My interpretation of this is that a protein antigen not only passes relatively intact from the GI tract of the mother into her blood, but is then incorporated into her breast milk without being completely broken down to amino acids and/or incorporated into human milk proteins. I always thought that proteins were almost completely broken down into, at most, a few amino acids long before absorption. The previous link suggests that relatively intact dietary protein is present in our blood.
Does this lend credibility to those who fear the biological activity from ingested proteins that are introduced into our food artificially as in the case of bovine growth hormone in cow's milk or Bt toxin in GE crops?
Anybody with some helpful information?


13 comments:

rob said...

A fellow member of the bay pointed out that she had heard that digestive enzymes are recycled. It seems it this is controversial and most evidence points to the conclusion that this does not occur.

Anonymous Coward said...

but even a small peptide may be the antigen... Reminds me of the paper a couple of years ago about the insulin plasmid ingested by mice (they bypassed the stomach to protect the DNA) and how the intestinal cells took them up and started expressing the protein...

Bayman said...

Who says the antigen is a protein?
Maybe it's a small molecule. Maybe the cows are on penicillin and the baby's got a penicillin allergy. Or etc..

J.Garlough said...

If your friend is consuming Canadian Dairy products, it's not likely related to bovine growth hormone.

Thought #1: I doubt she wants to experiment with her baby, but I'd be interested to hear if the same symptoms occur when consuming raw milk products (eg. raw milk cheese). Lactose-digesting enzymes and bacteria are removed during the pasteurization process and I wonder if pasteurization might eliminate that which could help break down those protein antigens too. Some states sell raw milk in grocery stores so if your friend lives south of our boarder it should be easy to get.

Thought #2: Some dairy farmers still send their cows out graze on billions of different living organisms and that certainly effects what gets into the milk (eg. feed a cow onions for a few days and you'll have onion milk). So if the kid's allergies are worse in the winter it might not be what the mother is eating but the cows...

rob said...

Good point about the small molecules, however, cross-allergy often occurs to soymilk in these cases. Which I would think don't have antibiotics. It also seems like there is quite a bit of confidence about it being a protein allergy. However I can't find a killer reference.
Also good point about the BGH, bad example for Canada. She is definitely drinking pasteurized milk so perhaps the symptoms would be worse with "raw" milk.
I guess your thought number 2 would be another additional step of "processing" (cow digestion) that doesn't destroy the antigen. So if that's true it would only make this weirder to me.

J. Garlough said...

Why might the symptoms be worse with raw milk? I was thinking the situation might actually improve when the mother ate raw milk products over pasteurized products...

It's more likely that both mother and baby is intolerant of pasteurized cow's milk than raw cow's milk, simply because some bacteria required for proper digestion are removed during the pasteurization process.

rob said...

Thanks for following up J. Garlough.
Doing a bit of reading it seems as if pasteurization does not cause a reduction in allergenicity, which I took as a gimme, so that's how I misinterpreted your comment.
So if there is any information at all that bacteria in raw milk digest some of the particularly antigenic proteins in milk then perhaps you are correct. I can't find any such information, and in fact I would think that the presence of any bacteria in the milk would increase any immune reaction. However, I could be wrong, it's still an interesting thought.

Bayman said...

Couldn't seem to access those "one allegry-one allergen" citations, so maybe it's not worth considering any other antigenic possibilities. But I doubt it.

If it was my kid, I'd want to know exactly what he/she was reacting to, as opposed to what some other people have been observed to respond to. In my brief perusal of pubmed, all the literature seems to clearly indicate that milk contains multiple antigens. That makes sense to me. Milk contains thousands of molecules, both organic and inorganic, of cow, microbial and exogenous origin. Many of these we already know can trigger allergic/immune response, (ie antibiotics, bacterial antigens), and there's no reason to think that any others would be incapable of doing so.

I'd start the experiments with milk from different sources, pasteurized vs non, etc, etc...then correlate with a mass spec profile on each.

And obviously, the fact that it passes from mother to child strongly suggests small molecule...

Steve said...

Hi Rob et al,

There have been studies on this.

Please read PRIMARY PREVENTION OF ATOPIC DERMATITIS IN BREAST-FED
INFANTS: WHAT IS THE EVIDENCE?
Through this link:
http://download.journals.elsevierhealth.com/pdfs/journals/0022-3476/PIIS0022347604001775.pdf

I haven't followed all references back to original sources, but it appears that food antigens (including milk, egg, and peanut) have been detected in breast milk, and may trigger immune responses in infants. Interestingly, it seems that a healthy intenstinal bacteria flora and properly modulated bilirubin levels in infants, along with particular cytokines in a mother's milk, play a role in determining the infant's degree of tolerance to such antigens.

Anonymous said...

Thanks Steve.
Finally read that reference. It is the primary references in that article that strongly suggest a protein allergen. However it is all correlative from what I can see.
rob

Anonymous said...

Hello,
I find this to be an important discussion, esp since my 10 yo son has an allergy to cow's milk. He is NOT allergic to RAW milk. The theory about bacteria aiding digestion in the milk is interesting. However, what if the pasteurization of the milk denatures the proteins and these denatured proteins are eliciting an immune response. Having said that, autoimmune disease start at the gut and having a GI tract that is fortified with protective intestinal flora is critical for health as well . If anyone has any thoughts on this, I would appreciate sharing of information. Jasmine sgilmian@rogers.com

Bayman said...

Interesting to hear your raw milk story. While traveling in Switzerland a few years back, I also found that my stomach tolerated raw milk cheeses and dairy much better than the pasteurized products I am used to here in Canada. I have no idea why; protein denaturation and destruction of good bacteria are both good guesses. I did search the scientific literature a while back and did find much on the topic.

There was a guy trying to sell raw milk in Ontario...last I heard they were trying to shut him down as selling raw milk is illegal in Canada. But you can find info on the web.

Also, you can always buy your own cow or befriend someone who has some.

Bayman said...

did NOT find much rather...