This review describes patients with schizophrenia and bipolar disorder. In such patients, a high inflammatory set point of circulating monocytes at the transcriptome level is observed, involving various inflammatory transcripts forming distinct fingerprints (the transcriptomic monocyte fingerprint in schizophrenia overlaps with that in bipolar disorder, but also differs with it at points). There are increased levels of compounds of the IL-1, IL-6 and TNF system in the serum (be it modest and inconsistent). There is also evidence that the IL-2 system is activated in patients with schizophrenia (and perhaps those with mania), although independently of the activation of the IL-1, IL-6 and TNF systems, suggesting separate inducing mechanisms for monocyte and T-cell activation. It is not yet known whether such T cell activation involves the Th1/Th2/Th17 or Treg systems.