Cancer and depression: cancer presenting with depressive illness: an autoimmune disease?

It is proposed that some cases of depressive illness in cancer patients may be caused by immunological interference with the activity of serotinin, one of the neurotransmitters thought to be implicated in depression. This interference could be mediated in two ways. Antibody induced against a protein released from cancer cells could, on the basis of cross-reactivity with CNS tissue, bind to receptors for serotonin and block them. Such primary antibodies could stimulate the production of anti-idiotypic antibodies, which would act as an alternative receptor for serotonin and reduce its synaptic availability.