CD40LG and myalgic encephalomeyelitis/chronic fatigue syndrome: In the analysis of Giardia antigen induced differences in cytokine profiles with regard to fatigue outcome we found only sCD40L to be significantly different within exposed groups (KruskalWallis p = 0.03) and the PI-CFS/PI-ICF groups having significantly elevated levels of sCD40L compared to the no PI-fatigue groups (Table 4).