Serum Bactericidal Activity and Induction of Chemiluminescence of Polymorphonuclear Leukocytes: Complement Activation Pathway Requirements in Defense against <i>Neisseria meningitidi</i><i>s</i>

Abstract

Serum bactericidal activity and chemiluminescence (CL) responses of polymorphonuclear leukocytes (PMNL) to pathogenic Neisseria meningitidis serogroups B and W-135 and to nonpathogenic serogroup 29E were examined with pooled normal human serum depleted of the complement proteins C1q, factor D, properdin and C5. Purified C1q, factor D, properdin and C5 were added alone or in combination. For investigation of serogroup W-135 meningococci, a C1q, factor D and properdin-depleted postvaccination serum with high concentrations of anticapsular antibodies was also used. Serogroup B and W-135 cultured to log phase were resistant to the bactericidal activity of pooled normal human serum but were efficiently killed through the classical pathway alone when the bacteria were cultured to stationary phase. Nonpathogenic serogroup 29E meningococci in log or stationary growth phases were efficiently killed in serum, predominantly through the classical pathway. Serogroup W-135 meningococci grown to log phase were resistant to classical pathway-mediated bactericidal activity in postvaccination serum but were killed on addition of alternative pathway proteins. Stationary phase serogroup W-135 meningococci were killed through both pathways in the postvaccination serum. In the pooled normal human serum CL responses of PMNL were consistently more pronounced with fully reconstituted C1q, factor D, properdin, C5-depleted serum than with serum reconstituted with C1q, factor D and properdin suggesting contribution of actions related to terminal components. In the absence of C1q, serogroup W-135 meningococci in postvaccination serum induced a significant but delayed alternative pathway-mediated CL response. CL responses induced by serum-opsonized meningococci, in contrast to serum bactericidal activity, were not influenced by culture conditions. The findings suggest that phagocytic mechanisms may be of critical importance for resistance to pathogenic meningococci in nonvaccinated adults.

The effects of live Neisseria meningitidis and tumour necrosis factor‐α on neutrophil oxidative burst and β2‐integrin expression

“…It has previously been shown that PMNL react differently when exposed to different serogroups of N. meningitidis. PMNL are stimulated to a higher degree by nonpathogenic than by pathogenic MC strains (7)(8)(9). In the present study it is shown that TNF-a causes a significant increase in the oxidative burst response when added at the same time as live MC to either isolated PMNL or whole blood.…”

“…In other studies, TNF-a was shown to increase the oxidative burst response and enhance killing of pathogens such as Staphylococcus aureus, Haemophilus infruenzae and fungi (4)(5)(6). Previous studies of PMNL-MC interactions using a chemiluminescence method (CL) have shown that the CL response to pathogenic and nonpathogenic serogroups of MC differs (7)(8)(9). The P2-integrin CD 1 1 b/CD18 is located on the surface of leukocytes and has importance for phagocytosis and adhesion (lo), and previous studies have shown that the expression of C D l l b/CD18 is increased when PMNL are stimulated with LPS or TNF-a (5, 11).…”

The role of Fcγreceptor polymorphisms and C3 in the immune defence againstNeisseria meningitidisin complement-deficient individuals

“…The increased phagocytosis of N. meningitidis W135 after opsonization with reconstituted properdin‐deficient serum was highly dependent on C3 deposition. This was supported by the effect of blocking complement receptor 3, the main receptor for C3‐mediated phagocytosis on PMN [33]. The relevance of C3 deposition by properdin is further supported by the correlation found between C3 deposition and phagocytic activity induced by (added) properdin.…”

Complement classical pathway components are all important in clearance of apoptotic and secondary necrotic cells

“…MBL activity was analysed by C4 deposition in MBLD serum to which rMBL was added [9]. The following complement proteins were available in the laboratory and published methods were used for purification of C1q [10], C4 [11], factor D [6] and properdin [12]. Purification of C2 was a modification of published protocol [13], where the separation of C2 from FB was achieved by affinity chromatography using NHS‐activated Sepharose (Amersham Pharmacia Biotech AB) coupled with rabbit anti‐C2 immunoglobulin G (IgG).…”