Allergies/Antigens

Allergies/antigens. Hypersensitivity Pneumonitis is caused by an exposure to an antigen: mold, fungus, organic dusts. Rarely is there a medical study regarding HP as it is almost impossible to prove what caused the disease. The specific antigen.

When I was first diagnosed, I would say that I was allergic to something, which kicked in my autoimmune system. The doctors kept correcting me saying it was actually caused by an antigen, not an allergy. No medical tests could actually prove what caused my disease but it was clear that the mold, fungus and rat dropping in the old portable classroom was the #1 suspect as my DLCO jumped when I was removed from the environment. But, really no medical proof. My Worker's Comp lawsuit was settled. 

I recently had a conversation with a woman whose husband had been diagnosed with HP in 2011. It was rather a shock to me that she was able to pinpoint the specific antigen, which was the goose down in their home. Feathers. Bird feathers are the #1 cause of HP. But, how did she know for sure?

She told me her story: The hospital "told us to bring in an industrial hygienist to vet the house and to discard or repair everything that could be a vector. After quite a bit of demo (sigh) to chase tiny amounts of mold and discarding all the feather stuff in the house, I finally reached a breaking point and insisted on visiting an allergist. The hospital had been vehemently opposed to this step, but we found that it explained everything. The blood serum results were consistent with the responses to what we were doing in the house and his PFT numbers. I still don't quite understand why the hospital was so adamant about not engaging an allergist. Once we removed all the feathers, his numbers started to improve. It took a month or two, but the improvement was steady. A huge relief."

I changed some of the above to remove his name and the name of the hospital.

In further conversations:

•                The first round of testing was blood serum testing. That was what revealed the avian protein issues. This round of testing was done in, maybe, summer 2011.

•                The second round of testing was skin testing. The second round was done this summer. 

•                If you're on an immune suppressant, there's a good risk of false negatives. The allergist always intended to retest if he was ever able to be weaned off the Cellcept. 

•                The occupational med doc at the hospital was vehemently opposed to any allergy testing. She told us it would "only confuse things." She also told us that HP could only be caused by avian proteins or mold. She told us that we had to keep fixing or discarding things in the house until his PFTs started to improve. Given that there's a delay between action and test/test result, this seemed like a pretty imperfect approach.

•                The allergist had worked with HP patients in the past, and testing make perfect sense to him.

Allergy tests? So interesting!

All of this made we wonder why allergy tests are not part of the protocol when one is diagnosed with HP? It may not be perfect but if it quickly points the patient in the direction of the antigen, and that patient is removed from it, the lungs may not be permanently damaged. They can repair and recover. Time and exposure are deadly. 

So, with this in mind, I asked my friend about the allergy/antigen issue. She is in her late 60s but was a working biologist doing research on drugs and DNA during her career. Here is her response to my question of why doctors do not do allergy testing for HP:

"The problem with the immune system, particularly antibodies, is that the diversity achievable is so extreme through all the genetic tricks available that some antibodies can be generated that will react with your own tissue--the very definition of an autoimmune disease.  There are safe
guards against this, but sometimes antibodies slip through the editing process.  What antibodies
react with and bind to is called the antigen.  But there may be crossreactivity with some part
of your own tissue--and that is what causes the disease."

She is way too smart for me. I think what she is saying is there is a hugely different response to the body between an allergy vs. an antigen. I think. 

Moving forward, I am going to bring this subject to the ILD Support Group and ask for a doctor to come to a meeting to explain why allergy testing is not part of the protocol for treating HP. To be continued.