IL15 and rheumatoid arthritis: Additionally, HuMax-IL-15, a human IgG1 anti-IL-15 monoclonal antibody, that in vitro was able to neutralize exogenous and endogenous IL-15, has been used for clinical trials in patients with RA to perform a phase I–II dose-escalation trial (Baslund et al., 2005; Waldmann, 2006).