The role of complement in anti-bacterial defence

Area of Science:

• Immunology
• Infectious Diseases
• Genetics

Background:

• The complement system is crucial for host defense against pathogens.
• Late complement component deficiencies (LCCD) are linked to Neisseria infections, particularly meningococcal disease.
• Understanding LCCD's impact on meningococcal susceptibility and immune response is vital for public health.

Purpose of the Study:

• To investigate the association between LCCD and meningococcal meningitis in an Italian population.
• To analyze the immune response to meningococcal vaccination in individuals with LCCD.

Main Methods:

• Analysis of complement profiles in survivors of meningococcal meningitis.
• Identification of LCCD prevalence (homozygous C6, C7, C8 deficiencies).
• Measurement of anti-polysaccharide antibodies before and after vaccination in families with LCCD.

Main Results:

• 17% of studied survivors had homozygous LCCD (C8, C7, C6 deficiencies).
• All LCCD subjects were infected with meningococcal serogroup C, which appeared less immunogenic.
• Homozygous LCCD individuals had higher pre-vaccination antibody levels but a blunted response post-vaccination.

Conclusions:

• Confirms a strong association between homozygous LCCD and invasive meningococcal disease in Italy.
• Homozygous LCCD subjects exhibit impaired antibody response to meningococcal polysaccharide vaccination.
• LCCD represents a significant risk factor for severe meningococcal infections and impacts vaccine efficacy.