Mannan binding lectin in febrile adults: no correlation with microbial infection and complement activation

Area of Science:

• Immunology
• Complement System Biology

Background:

• The mannan-binding lectin (MBL) pathway is a key component of the innate immune system, crucial for host defense against microbial pathogens.
• Understanding the role of MBL in vivo is essential for comprehending host-pathogen interactions and infectious disease outcomes.

Purpose of the Study:

• To investigate the role of the MBL pathway in host defense against microbial infections.
• To determine the association between MBL levels and infectious mortality in a general hospital patient population.

Main Methods:

• A prospective observational study involving 177 hospitalized medical patients presenting with new-onset fever.
• Assessment of infection presence, origin, and microbial cause, alongside measurements of MBL and complement activation product C3a.
• Monitoring of patient outcomes over a 28-day hospital course.

Main Results:

• Patients exhibited MBL levels comparable to healthy individuals, with MBL deficiency observed in 18% of patients and 14% of blood donors.
• Microbiologically confirmed infections correlated with higher C3a levels, but MBL levels or deficiency frequency did not differ significantly across infection groups.
• Overall mortality was 8%, with no significant differences in MBL levels between outcome groups.

Conclusions:

• The findings suggest that the MBL pathway does not play a predominant role in the host defense against serious microbial infections in non-selected adult patients.
• MBL deficiency does not appear to be a significant predisposing factor for severe or invasive microbial infections in this population.
• Microbial infection in hospitalized febrile adults activates the complement system independently of MBL levels.