PRDM1 and AL amyloidosis: Early RA pDCs were characterized by striking downregulation of TNFRSF17 with upregulation of PRDM1 and CSF1R. TNFRSF17 (BMCA) is increased upon TLR engagement (77) and is expressed at high levels on pDCs from multiple myeloma patients, where there is pathogenic expansion of plasma cells (78).