Cell https://doi.org/10.1016/j.cell.2017.11.036 (14 December 2017)

Natural killer T cells (NKT cells) respond to glycolipid antigens presented on CD1 molecules and contribute to anti-bacterial humoral responses by providing cognate help to B cells. In Cell, Gaya et al. show that NKT cells also promote antibody responses during viral infection. Mice lacking CD1d develop fewer germinal centers and less virus-specific immunoglobulin G1 than do wild-type mice. NKT cell help is indirect and occurs by day 3 after infection, before the formation of germinal centers, at the periphery of B cell follicles via their elaboration of IL-4. CD1d+CD169+ macrophages release the IL-18 that is needed for NKT cell activation and IL-4 production. This early wave of IL-4 released by NKT cells thereby enhances B cell antibody responses after viral infection.