Interleukin-2 receptor subunit beta (IL2RB, IL2Rβ) and Cytokine receptor common subunit gamma (IL2RG, IL2Rγ) is tyrosine phosphorylated after Interleukin-15 (IL15) / IL15 receptor complex interaction (Adunyah et al. 1997, Zambricki et al. 2005). More in detail, human and mouse IL15 have 70.2% amino acid sequence similarity and exhibit similar trans-presentation mechanism, signal transduction machinery and biological activities. Similarly, human IL15 shows cross-reactivity with mouse cells and it was demonstrated that human and mouse IL15 showed similar responses in mouse models (Stoklasek et al. 2006) (Patidar et al. data not published). This is a black box event because more evidence to support this reaction is needed.