C5 deficiency

Classical and alternative complement pathways converge in C5 complement factor, to activate the lytic pathway

• mainly synthesized by hepatocytes, but also by monocytes, lymphocytes and lung, spleen and fetal intestine cells
• C5 gene is located in chromosome 9q34.1
• C5 complement deficiency
  • a rare autosomal recessive inherited disease, associated with recurrent infections episodes, particularly meningitis and extragenital gonorrhea by Neisserial species - these are the most frequent micro-organisms isolated in these patients (1)
    • explained because sera from C5 deficiency patients lack bactericidal activity and have severely impaired ability to induce chemotaxis (2)

Reference:

1. Peter et al.Meningoccocal meningitis in familial deficiency of the fifth component of complement. Pediatrics 1981;67: 882–886.
2. Wetsel, 2000 Wetsel, R.A., 2000. The complement. In: Morley, B.J., Walport, M.J., (Eds.), Facts Book Series, Academic Press, pp. 104–109.