Increased complement classical and mannan-binding lectin pathway activities in schizophrenia

Neurosci Lett. 2006 Sep 1;404(3):336-41. doi: 10.1016/j.neulet.2006.06.051. Epub 2006 Jul 24.


Schizophrenia is a severe mental disorder, with worldwide prevalence of 1-1.5%. Immunological research in schizophrenia indicates that infectious or autoimmune processes might play a role in the etiopathogenesis. The complement system is a major mediator of innate immune defence against infection and contributes to many functions of the immune system including inflammation, opsonization and cell lysis. Mannan-binding lectin (MBL) activates the complement system via the lectin pathway. Inherited MBL deficiency, common in most human populations, predisposes to infectious and autoimmune diseases. We measured total complement activity (CH50), C4 activity (C4 CH50), MBL level and the activities of MBL-associated serine proteases, MASP-1 and MASP-2 in sera of 45 schizophrenic patients and in 62 healthy volunteers. We found that schizophrenic patients and healthy volunteers have statistically similar MBL levels and MASP-1 activity. However, MBL-bound MASP-2 activity and therefore MBL and MASP-2-mediated complement activation capacity is increased in schizophrenic patients compared with healthy volunteers (P<0.01). The increase was accompanied by increased CH50 (P<0.02) and C4 CH50 (P<0.02). Our results support the idea that complement system alterations may be involved in schizophrenia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Complement C4 / analysis
  • Complement Pathway, Classical*
  • Complement Pathway, Mannose-Binding Lectin*
  • Female
  • Humans
  • Male
  • Mannose-Binding Lectin / blood
  • Mannose-Binding Protein-Associated Serine Proteases / analysis
  • Middle Aged
  • Schizophrenia / immunology*


  • Complement C4
  • Mannose-Binding Lectin
  • MASP1 protein, human
  • MASP2 protein, human
  • Mannose-Binding Protein-Associated Serine Proteases