Waldenström macroglobulinemia cell (B cell)-Treg cell cross talk. WM cells modulate Treg cell expansion and promote their immunosuppressive activity through CD40/CD40-ligand interaction, creating an immunosuppressive milieu, which in turn supports WM cell proliferation. CD40/CD40L axis blockade reverses this phenomenon. IL-10, interleukin-10; TCR, T-cell receptor; TGFB, transforming growth factor β. Figure created with BioRender.com.