CX3CR1 and immune system disorder: Further investigation of human immune disorders uncovers the dynamic complexity of the CX3CL1/CX3CR1 axis: In systemic lupus erythematosus (SLE), CX3CR1 expression in B cells/plasmablasts is negatively regulated by Notch signaling [204]—a mechanism absent in murine models, indicating broader immune regulatory hierarchies in humans.