Some other interleukins, such as IL-1RA, IL-10 and IL-15 [34], were also found to be increased in schizophrenia, while IL-6R, cluster of differentiation 5-like protein (CD5L), also known as apoptosis inhibitor expressed by macrophages, and IL-17 were even proposed to be a differentiating factor between pre-onset schizophrenia and bipolar disorder [35]. Here, CD5L is linked to schizophrenia.