I have read with interest Klimas et al's work on CD26 and CFS. The thought is that this marker is very low in CFS. I have done some research, CD26 is also known as Dipeptidyl peptidase-4 (DPP4). I found it very interesting to learn that DPP4 has found growing use in Digestive Enzyme supplements, specifically to help digest casein and gluten. I thought this was very interesting as many people with CFS have wheat or milk allergies / intolerances. Could there be a connection here, or is this mere coincidence? And given Klimas et al think CD26 is very low in CFS, does this supplement form help?