Your question about a test for IL-17, etc. to determine whether interferon-b will work for individual patients reminds me of this recent study:http://www.theaustralian.com.au/news/breaking-news/vitamin-d-links-to-ms-supported-by-study/story-fn3dxiwe-1226436839179
The study showed that:
Interferon-beta caused patients to become far more efficient at making vitamin D in their skin
Interferon-beta only reduced the risk of having an MS attack if patients had sufficient levels of vitamin D in their system
This made me wonder if there is some relationship between the test you describe for the effectiveness of Interferon-B for individual patients, and the patients' individual vitamin D levels?
So I found this study:http://www.msfocus.org/news-details.aspx?newsID=190
which says that Vitamin D works to reduce MS relapses by suppressing IL-17. IL-17 is one of the things the test you mentioned tests for.
So that made me wonder if what the test you mentioned does is indirectly test for how high a patient's vitamin D level is by checking to see how high their IL-17 level is?
If a patient's IL-17 level is low, that could mean that they have sufficient Vitamin D in their system for Vitamin D to be able to down regulate IL-17. In small studies Vitamin D3 has been shown to dramatically reduce Multiple Sclerosis Relapse rates: http://www.webmd.com/multiple-sclerosis/news/20090428/high-doses-vitamin-d-cut-ms-relapses
So my last question is, do the Interferon-B drugs actually work at all? Or should I say, is their mechanism of action merely that they increase vitamin D levels? And If that was the case, wouldn't it make more sense to just directly take optimal doses of Vitamin D3, instead of letting the drug boost your level, at the risk of suffering side affects?
I'm not a scientist or a doctor, and my MS does affect my cognition, so please don't make decisions based on what I say. Do your own research, and make your own decisions after consulting the the health care provider of your choice.
But I thought I'd throw my thoughts, questions and google research out here for wiser minds to contemplate.