TNF and myeloid sarcoma: As a corollary, atacicept,134 which neutralizes BAFF (B-cell activating factor) and APRIL (a proliferation-inducing ligand), and anti-TNF-alpha (infliximab and lenercept),135 which have both been shown to exacerbate MS disease activity, are known to expand peripheral memory B-cell numbers.42 Memory B cells as a therapeutic target may be critical in explaining the effects of therapeutic agents in MS.