Extended Data Figure 6. Expression of Ggt5 by human tonsil follicular dendritic cells and fragmentation pattern of S-geranylgeranyl-L-Cys-Gly.

(a) P2RY8 ligand bioassay on supernatants from HEK293T cells transfected with the indicated enzymes (n=4 biological replicates). (b) Positive ion mode MS/MS spectra of the m/z 451.3 metabolite from extracts of the type in Figure 4d, corresponding to S-geranylgeranyl-L-Cys-Gly. (c) Immunohistochemistry for GGT5 or CR2 (brown), in serial sections of human tonsil, counterstained with hematoxylin (blue). Scale bars, 200 μm. (d) Immunofluorescence for GGT5 (green), CR2 (red), and DAPI (blue) in tonsil sections. Serial sections were stained for P2RY8 (green) and DAPI (blue) to visualize the difference between FDC-extensions and GC B-cell membranes. The indicated regions in the upper panels (scale bars, 100 μm) are enlarged in the lower panels (scale bars, 25 μm). (e) qPCR for GGT5 in the indicated tissues and cells from human tonsil, relative to GAPDH. Points within each category represent individual tonsils (whole tonsil=4, tonsil stroma=4, bulk lymphocytes=4, FoB=2, GC B=3, CXCR5^- CD4⁺ T=3, CXCR5^int CD4⁺ T=2, Tfh=3). Data are representative of or pooled from 2 (a,b) independent experiments and data in (c, d) are representative of 4 tonsil specimens. Graphs depict mean with s.d.