Furthermore, the PD-1/PD-L1 pathway is altered in MS and elevated PD-1/PD-L1 expression has been associated with disease remission in MS patients.50, 51 It is tempting to speculate that repetitively enhanced expression of PD-1 (that is, receptor exhaustion), possibly as an immune escape mechanism for B-LCLs, would have consequences for subsequent PD-1 functionality or expression. Here, PDCD1 is linked to myeloid sarcoma.