Mannose-Binding Lectin Binds to a Range of Clinically Relevant Microorganisms and Promotes Complement Deposition

TLDR

Mannose‑binding lectin is a collagenous serum lectin that plays a key role in innate immunity, and genetically low levels predispose individuals to infections. The study investigated the binding of purified MBL to pathogens isolated from immunocompromised children. Binding was assessed using flow cytometry. MBL bound strongly to Candida species, Aspergillus fumigatus, Staphylococcus aureus, and β‑hemolytic group A streptococci, showed heterogeneous binding to E.

Abstract

ABSTRACT Mannose-binding lectin (MBL) is a collagenous serum lectin believed to be of importance in innate immunity. Genetically determined low levels of the protein are known to predispose to infections. In this study the binding of purified MBL to pathogens isolated from immunocompromised children was investigated by flow cytometry. Diverse Candida species, Aspergillus fumigatus , Staphylococcus aureus , and beta-hemolytic group A streptococci exhibited strong binding of MBL, whereas Escherichia coli , Klebsiella species, and Haemophilus influenzae type b were characterized by heterogeneous binding patterns. In contrast, beta-hemolytic group B streptococci, Streptococcus pneumoniae , and Staphylococcus epidermidis showed low levels of binding. Bound MBL was able to promote C4 deposition in a concentration-dependent manner. We conclude that MBL may be of importance in first-line immune defense against several important pathogens.