Related Experiment Videos
Granulocyte functions and Neisseria meningitidis: influence of properdin-deficient serum
C Söderström1, J H Braconier, A G Sjöholm
1Department of Infectious Diseases, University of Lund, Sweden.
Abstract:
Granulocyte-mediated reactions such as opsonization, chemotaxis, and release of granulocyte myeloperoxidase and lactoferrin were studied in properdin-deficient and normal human serum incubated with serogroup A and W-135 meningococci. There were no differences between the sera when serogroup A meningococci were studied. Opsonic and chemotactic activity were impaired against serogroup W-135 meningococci in properdin-deficient serum. Restitution with properdin restored both activities. We found similar release of myeloperoxidase and lactoferrin from granulocytes challenged with serogroup A or W-135 meningococci in either sera. These findings are in accordance with the clinical observations of meningococcal infections caused by serogroup W-135 in properdin-deficient patients as well as the absence of infections caused by serogroup A meningococci.
Insights
Properdin deficiency impairs immune responses to W-135 meningococci but not serogroup A. This explains why properdin-deficient patients suffer W-135 infections, unlike those caused by serogroup A meningococci.
Area of Science:
- Immunology
- Microbiology
- Complement System
Background:
- Properdin is a key complement factor crucial for innate immunity against Neisseria meningitidis.
- Deficiency in properdin leads to increased susceptibility to meningococcal disease.
Purpose of the Study:
- To investigate the impact of properdin deficiency on granulocyte-mediated immune reactions against serogroup A and W-135 Neisseria meningitidis.
- To correlate in vitro findings with clinical observations in properdin-deficient individuals.
Main Methods:
- Incubation of properdin-deficient and normal human serum with serogroup A and W-135 meningococci.
- Assessment of granulocyte opsonization, chemotaxis, and release of myeloperoxidase and lactoferrin.
- Restitution of properdin-deficient serum with purified properdin.
Main Results:
- No significant differences in granulocyte-mediated reactions were observed with serogroup A meningococci between normal and properdin-deficient sera.
- Opsonic and chemotactic activities against serogroup W-135 meningococci were significantly impaired in properdin-deficient serum.
- Restoration of properdin normalized these activities against serogroup W-135.
- Similar release of myeloperoxidase and lactoferrin occurred regardless of meningococcal serogroup or properdin status.
Conclusions:
- Properdin deficiency selectively impairs immune responses to serogroup W-135 meningococci, explaining clinical susceptibility.
- Immune responses to serogroup A meningococci are not affected by properdin deficiency.
- These findings highlight the specific role of properdin in defense against certain meningococcal serogroups.