PRL and systemic lupus erythematosus: With respect to the differentiation of CD4+ Th cells, PRL up-regulates the levels of INF-γ, IL-12, IL-2, and CD40L (Clevenger, Altmann & Prystowsky, 1991; Clevenger et al., 1990; Gonzalez, Saha & Peeva, 2013; Jara et al., 2017; Matalka, 2003; Mukherjee, Mastro & Hymer, 1990; Orbach et al., 2012), leading to CD4+ T cell activation that can drive the development of autoimmunity in SLE.