IL21 and infection: Interestingly, there was no positive correlation seen between baseline IL-21R expression and the response of plasma cell frequencies to IL-21, suggesting that the plasma cell response to IL-21 at 3 dpi in KSHV infected cultures may be a product of IL-21 receptor up-regulation in response to infection instead of intrinsic baseline levels of IL-21R on plasma cells in our tonsil lymphocyte cultures.