Further establishing the B-helper capacity of TH17 cells, a recent study showed that IL-17, when combined with BAFF, a cytokine also upregulated in MS patients, promoted B cell survival, proliferation, and differentiation into PCs, providing a second method by which TH17 cells can promote GC-like B cell responses within the CNS (120). Here, IL17A is linked to myeloid sarcoma.