The role of C9 in complement-mediated killing of Neisseria

G. R. Harriman, A. F. Esser, E. R. Podack, A. C. Wunderlich, A. I. Braude, T. F. Lint, J. G. Curd

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45 Scopus citations


During the routine examination of a healthy 31-yr-old woman, we found an incomplete deficiency of the 9th component of complement (C9). By hemolytic assay her serum C9 activity was 10 to 15% of normal. Limited family studies suggested that she inherited the deficiency as an autosomal codominant trait. She had no history of unusual or severe infections. When tested for bactericidal activity against serum-sensitive Neisseria gonorrhoeae and N. meningitidis, her serum reacted comparably to normal serum. Normal serum depleted immunochemically of C9 and sera from congenitally C9-deficient patients were also bactericidal against serum-sensitive Neisseria but required 120 min to kill the same numbers of gonococci that intact serum killed within 30 min. In the electron microscope, N. gonorrhoeae incubated with C9-depleted serum were fragmented but lacked the typical C lesions. Therefore, serum lacking C9 can kill serum-sensitive Neisseria, unlike sera deficient in the other terminal C components.

Original languageEnglish (US)
Pages (from-to)2386-2390
Number of pages5
JournalJournal of Immunology
Issue number6
StatePublished - 1981

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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