Additionally, while interactions between CD74 and COPA (COPI coat complex subunit alpha) of malignant plasma and immune cells have been described in Waldenstrom macroglobulinemia (164), these interactions have also been shown to play a role in the maturation of B cells in the setting of antibody-mediated renal transplant rejection (165). This evidence concerns the gene COPA and Waldenstrom macroglobulinemia.