Human alveolar macrophage cytophilic immunoglobulin G-mediated phagocytosis of protein A-positive staphylococci.
AUTOR(ES)
Verbrugh, H A
RESUMO
Human alveolar macrophages (AM) have recently been reported to ingest and kill a strain of Staphylococcus (502A) in the absence of opsonins. To further investigate the mechanism of non-opsonic recognition, we studied phagocytosis of 23 clinical and laboratory strains of S. aureus and Staphylococcus epidermidis by AM, and by blood polymorphonuclear leukocytes (PMN) and monocytes (MN). In the absence of opsonins, AM phagocytized 18 protein A-positive but not 5 protein A-negative strains of staphylococci, and the efficiency of phagocytosis directly correlated with the amount of protein A present in the bacterial cell wall (r = 0.86, P less than 0.001). Furthermore, AM rosetted around protein A-coated Sepharose beads, but not around beads without protein A. In contrast, PMN did not phagocytize nonopsonized staphylococci, and did not rosette around either type of Sepharose. MN phagocytized protein A-positive staphylococci, but much less efficiently than AM, and showed some rosetting around protein A-coated Sepharose. The nature of the AM receptor for protein A-positive staphylococci was studied. The surface of AM was positively stained with fluorescein-conjugated antibody to human IgG, but not with IgA- or IgM-specific conjugates. No such surface-immunoglobulins were detected on PMN, and MN were only weakly positive for surface IgG. Pretreatment of AM with F(ab')2 fragments specific for human IgG (anti-Fc) inhibited subsequent phagocytosis of protein A-positive staphylococci. There was no evidence that the AM surface IgG was aggregated or immunecomplexed. From these studies we conclude that human AM possess cytophilic IgG antibodies, which can function as receptors for phagocytosis of protein A-positive staphylococci.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=371169Documentos Relacionados
- Mechanism of inhibition of immunoglobulin G-mediated phagocytosis by monoclonal antibodies that recognize the Mac-1 antigen.
- Antagonist G-mediated targeting and cytotoxicity of liposomal doxorubicin in NCI-H82 variant small cell lung cancer
- Staphylococci-induced Human Platelet Injury Mediated by Protein A and Immunoglobulin G Fc Fragment Receptor
- Immunoglobulin G enhances C3 degradation on coagulase-negative staphylococci.
- Immunoglobulin G-induced single ionic channels in human alveolar macrophage membranes.