IL6 and visceral leishmaniasis: However, in visceral leishmaniasis, several factors like the well-characterized polyclonal B-cell activation (36,37) and production of cytokines [e.g. IFN-γ, IL10 (38–41), and IL6 (42,43)] and chemokines (e.g. CXCL12) may contribute to plasma cell differentiation and retention in the red pulp (44).