Mannose-binding lectin deficient mice are susceptible to infection with Staphylococcus aureus

Gram-positive organisms like Staphylococcus aureus are a major cause of morbidity and mortality worldwide. The mannose-binding lectin (MBL) recognizes a broad range of infectious agents including S. aureus. Circumstantial evidence suggests that MBL plays a key role in first line host defense. We tested this contention in vivo by generating mice that were devoid of all MBL activity. We found that 100% of MBL-null mice died 48 h after an intravenous inoculation of S. aureus compared with 45% mortality in wildtype mice. Furthermore, we demonstrated that neutrophils and MBL are required to limit intraperitoneal infection with S. aureus. The phenotype was reversed by reconstitution with exogenous MBL. Our study provides direct evidence that MBL plays a key role in restricting the complications associated with S. aureus infection in mice and may act as a disease susceptibility gene against staphylococci infections in humans.