Antibody dependent complement activation is critical for boosting opsonophagocytosis of Staphylococcus epidermidis in an extremely preterm human whole blood model.

Staphylococcus epidermidis is a major cause of late onset sepsis in extremely preterm neonates. Antibody therapies are considered as an interesting strategy to prevent sepsis. However, previous clinical trials with intravenous immunoglobulin (IVIG) and a monoclonal antibody (mAb) targeting staphylococcal lipoteichoic acid (LTA) (Pagibaximab) failed to show significant protection from invasive infections in extremely preterm neonates.

Agnostic B cell selection approach identifies antibodies against K. pneumoniae that synergistically drive complement activation.

Antibody-dependent complement activation plays a key role in the natural human immune response to infections. Currently, the understanding of which antibody-antigen combinations drive a potent complement response on bacteria is limited. Here, we develop an antigen-agnostic approach to stain and single-cell sort human IgG memory B cells recognizing intact bacterial cells, keeping surface antigens in their natural context.

Toward Understanding How Staphylococcal Protein A Inhibits IgG-Mediated Phagocytosis.

IgG molecules are crucial for the human immune response against bacterial infections. IgGs can trigger phagocytosis by innate immune cells, like neutrophils. To do so, IgGs should bind to the bacterial surface via their variable Fab regions and interact with Fcγ receptors and complement C1 via the constant Fc domain.

Monoclonal antibodies effectively potentiate complement activation and phagocytosis of in neonatal human plasma.

Central line associated bloodstream infections (CLABSI) with are a major cause of morbidity in neonates, who have an increased risk of infection because of their immature immune system. As especially preterm neonates suffer from antibody deficiency, clinical studies into preventive therapies have thus far focused on antibody supplementation with pooled intravenous immunoglobulins from healthy donors (IVIG) but with little success. Here we study the potential of monoclonal antibodies (mAbs) against to induce phagocytic killing by human neutrophils.

Host-Receptor Post-Translational Modifications Refine Staphylococcal Leukocidin Cytotoxicity.

Staphylococcal bi-component pore-forming toxins, also known as leukocidins, target and lyse human phagocytes in a receptor-dependent manner. S-components of the leukocidins Panton-Valentine leukocidin (PVL), γ-haemolysin AB (HlgAB) and CB (HlgCB), and leukocidin ED (LukED) specifically employ receptors that belong to the class of G-protein coupled receptors (GPCRs). Although these receptors share a common structural architecture, little is known about the conserved characteristics of the interaction between leukocidins and GPCRs.