In TLSs, PD-L1 could act both as an “organizer” of germinal centers (as in secondary lymphoid organs) and as an inhibitor of the effector functions; hence, in MS inflamed meninges, through pathogenic events mediated by the EBER-TLR3/FDC-PD-L1 axis, the virus itself may promote the development of TLSs, using them as a protected reservoir of infected cells. Here, CD274 is linked to myeloid sarcoma.