Though prolactin disruption is not essential for the normal development and functionality of the immune system,244 prolactin can synergize with IL2 in B cell activation and differentiation.245 In addition, the prolactin receptor is expressed on human immune cells including T and B lymphocytes and monocytes,246 suggestive of its promotive roles in SLE development. This evidence concerns the gene PRL and systemic lupus erythematosus.