The article is mostly about how there are now recognized to be certain schizophrenia-like conditions that are clearly autoimmune diseases. Mentioned in the article are anti-NMDA-receptor encephalitis, which responds to immunotherapy, and a previously published case of a woman mid-diagnosed with catatonic schizophrenia fully recovering after being treated for lupus with immunosuppressive therapy.
Based on this, the article suggests that the rituximab Mary was given along with chemo was the key. However, they were unable to test conclusively for antibody evidence of this theory after the fact.