Distinct and overlapping functions of allelic forms of human mannose binding protein

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Human mannose binding protein (MBP) is a C-type serum lectin crucial for innate immunity.
• MBP plays a vital role in defending against bacterial, fungal, and viral pathogens.
• Low serum MBP levels have been associated with increased recurrent infections in infants.

Purpose of the Study:

• To investigate the functional significance of the Gly54Asp MBP genotype.
• To determine if the Gly54Asp allele explains low MBP levels and recurrent infections.
• To explore the allelic variations of MBP and their impact on complement activation.

Main Methods:

• Genotyping analysis to identify the prevalence of the Gly54Asp MBP allele.
• Functional assays to assess the protein encoded by the Gly54Asp genotype.
• Comparison of complement activation pathways between different MBP allelic forms.

Main Results:

• The Gly54Asp genotype occurs in 5% of the population.
• This genotype encodes a functional MBP protein.
• The Gly54Asp allele does not cause a deficiency state but suggests two predominant MBP allelic forms with differing classical complement pathway activation.

Conclusions:

• The Gly54Asp MBP genotype is not responsible for MBP deficiency.
• MBP likely exists in at least two functional allelic forms.
• These allelic forms possess overlapping functions but differ in their capacity to activate the classical complement pathway.