ID1 and hydrops fetalis: Similar to the No Tfh group, abrogation of IL18 signalling in Tfh was associated with a decrease in GC B cells, IgG MDA-LDL, IgM-CuOx-LDL, IgM-MDA-LDL, and IgM T15/E06 id+ antibodies (Figure 2A–F), as well as an accumulation of MZB cells (Figure 3A), further supporting a role for Tfh–MZB cell interaction in regulating the humoral response during HF/HC diet–induced atherosclerosis.