VDR and systemic lupus erythematosus: Our validation analysis in NZB/NZW F1 B cells demonstrated decreased mRNA and protein levels of VDR, which mediates the pleiotropic immunological effects of vitamin D. Of note, several SLE cohorts have low vitamin D levels, and addition of vitamin D to PBMCs results in a significant reduction of polyclonal and anti-dsDNA antibody production by SLE B cells through direct inhibition of their differentiation [26].