It seems that the most appropriate description would be that PD-1 is expressed in contexts of inhibition, rather than contexts of exhaustion per se, in so far as “exhaustion” is generally used when PD-1 is expressed in a context that is detrimental to the organism, but not when the context is beneficial (e.g., in peripheral tolerance during autoimmunity [60] or during T-cell memory formation [58]). This evidence concerns the gene PDCD1 and Autoimmunity.