For myself I have always thought there was an allergy connection to my autoimmune conditions. Many people who suffer from autoimmune conditions report an intolerance to cow's milk or wheat. I have done the elimination diet many years ago through the Royal Prince Alfred Hospital Allergy Clinic and definately discovered intolerance to wheat and dairy.
I will try and post links relating to this here
IS THERE A LINK BETWEEN IGAN AND ALLERGIES
GLUTEN SENSITIVITY from Gluten Intolerance Group
Could Gluten Be Causing Your Health Problems? from Gluten Intolerance Group