Interleukin-21 administration to rhesus macaques chronically infected with simian immunodeficiency virus increases cytotoxic effector molecules in T cells and NK cells and enhances B cell function without increasing immune activation or viral replication

► IL-21 administration to chronically SIV infected RM was safe and biologically active. ► IL-21administration increases cytotoxic effector molecules perforin and granzyme B in T cells and NK cells. ► IL-21 treatment increases memory B cell pool and anti-SIV Ab levels. ► IL-21 administration did not alter immune activation or plasma SIV RNA levels.