FCER2 and colorectal cancer: In colorectal cancer, multi-parameter immunofluorescence detection of CD21, CD23 and CXCL13 revealed three different states of TLS maturation: (i) early TLS as dense lymphocytic aggregates; (ii) primary follicle-like TLS, composed of B cell clusters with FDC networks, but devoid of GCs; and (iii) the secondary follicle-like TLS, including active GCs with CD23+ B cells (Posch et al., 2018).