Lymph node immunotherapy may be simpler, safer

A new, improved method of immunotherapy is emerging: injection of modified allergen, directly to the lymph node--which promises to prevent allergy to specific triggers with only a few treatments and minimal risk.

A group of Swiss, German, and Swedish scientists reports in the latest issue of the Journal of Allergy and Clinical Immunology that they reduced nasal tolerance of cat dander, a major trigger for atopic allergy, by a factor of 74 in a group of 20 subjects, using only three injections over two months. That means it took 74 times as much dander to cause the same amount of allergic reaction--the scientists used the flow of liquid from the nose as their measure--in a treated person as in a subject given placebo.

[This article featured in JACI's Journal Club.]

Immunotherapy for specific allergens currently requires 30 to 80 injections over three to five years and includes a risk of anaphylactic reaction. It is not popular. The new method, if confirmed, looks much more practical.

The researchers, Gabriela Senti of University Hospital Zurich and colleagues, were basically repeating an earlier, successful study that they had done with grass pollen. (I consider cat allergy avoidable but grass pollen is a big deal--you can't get away from it, unless you're in Antarctica.)

But the new study came with a twist--the researchers modified the cat dander allergen with two molecular changes. The first added a short chain of amino acids that helped the allergen enter the cell membrane--essentially, the membrane of B and T cells, since it was injected into the lymph nodes. This seems to have prevented other white blood cells, such as macrophages and mast cells, from encountering the allergen and provoking inflammation.

The second modification ensured that the allergen didn't get immediately destroyed inside the cells, but instead got chopped up and presented on the surface of antigen-presenting cells, which are a key element of the antibody arm of the immune system. Thus, by a process I don't really understand, your immune system becomes "tolerant" to that allergen.

Treatment with the modified cat allergen did not increase IgE antibody levels, or induce any "adverse events" in the treated group, which, it has to be said, numbered only 12. It's possible that in a larger test group some problems might reveal themselves.

If an environmental allergy is a big problem for your eczema, and you can stand nurses injecting things into your lymph nodes, this looks like good news. I don't know how long it might be until the FDA approves this treatment in the US though.

The sweet smell of dog

About that University of Cincinnati study. General feeling being that having a dog as a pet can only be a good thing for your baby because intense exposure to dog aeroallergen somehow has a long-term anti-inflammatory effect in those allergic to dogs, compared to cat aeroallergen, which is pure refined evil has a significant correlation with eczema at the age of 4 in kids with cat allergies.

Eczema seems to be a disease with a major autoimmune component.This kind of cohort survey research is constructive to the effort to find cures for eczema because it can highlight particular allergens and scientists can then look closely at what those allergens are doing to your immune system.

The authors mention collecting vacuum samples from the floors of people taking part in the study. They measured the concentrations of the major dog and cat allergens in dust. I was interested to find that they already know what these allergens are. These must be the active agents in skin prick tests.

It's a scientific paper so there's no mention made of this, but there should be: having a dog is a major undertaking. I know. About six years ago, Hidden B and I adopted an Australian cattle dog puppy. I loved the dog (didn't grow up with one; dad foisted a cat on us for a few years). I enjoyed going for a jog with her; going for a hike and throwing a tennis ball; trying and generally failing to teach her manners. But the work, the work. Picking up the poop in the backyard, which became a manicured latrine. Dealing with noise complaints from neighbors. Stopping the mutt from savaging the postman. And paying the kennel bill whenever we went on vacation. It was like having a kid. (In retrospect, good practice.) So you just can't expect a family with a history of atopy to casually take on caring for a dog.

But maybe someone can develop a reverse air purifier, which comes with a filter loaded with dog hair and dander, and blows a sweet, gentle doggy breeze into your house while you and your loved ones sleep.