NIH info on the immune system: 

Immune System NIH 

AND

Immunoglobulins high? - low?  Some definitions Maybe the levels are high ...  because you are dealing with an autoimmune issue ...  not a virus? (Well maybe the viruses, too, but not the bacteria)   Maybe the levels drop too low ...  because the immune system is 'wearing out'  due to over activity for 10+ years? The basics - to find diagnosis for fatigue      Autoimmune?