TNFRSF13B and lupus nephritis: Receptor-ligand expression analysis integrating kidney B cell and macrophage single-cell data supported BAFF as a major mediator of macrophage–B cell interactions but revealed differing BAFF receptor (BAFF-R) expression in lupus nephritis, with TNFSR13B (encoding transmembrane activator and cyclophilin ligand interactor, TACI) prominent in mediating interactions in lupus nephritis but TNFSR13C (encoding BAFF-R) dominant in control kidneys (Figure 8, F and G).