Opsonophagocytic effect of antibody against recombinant conserved 40-kDa outer membrane protein of Porphyromonas gingivalis.
BACKGROUND
Porphyromonas gingivalis is associated with the initiation and progression of adult periodontitis. The outer membrane proteins of the bacteria are potentially important targets for interaction with host defense systems. A 40-kDa outer membrane protein (40-kDa OMP) is conserved among many strains of P. gingivalis. We have cloned the gene for 40-kDa OMP from P. gingivalis 381 and produced a recombinant protein. For the development of recombinant 40-kDa OMP as a component of a vaccine for passive immunization, the elucidation of the roles of the anti-recombinant 40-kDa OMP antibody in the host defense against P. gingivalis is essential. The objective of this study was to determine the opsonic capacity of the antibody for phagocytosis by neutrophils which play a key role in the immune response to microbial infections.


METHODS
To test the opsonic activity of a rabbit polyclonal antibody against r40-kDa OMP (r40-kDa OMP Ab) on human neutrophils to phagocytize P. gingivalis, we constructed a reproducible in vitro model of P. gingivalis-neutrophil interaction using the human promyelocytic cell line HL-60.


RESULTS
We demonstrated that r40-kDa OMP Ab in the presence of human complement successfully opsonized [3H]-thymidine-labeled P. gingivalis as a target for phagocytosis by HL-60 cells differentiated with dimethyl sulfoxide. The phagocytized bacteria were then intracellularly killed and lysed, and the radioactive degradation debris egested into the culture medium.


CONCLUSIONS
We conclude that antibody against r40-kDa OMP has opsonic activity on human neutrophil function for phagocytosis of P. gingivalis. Subgingival bacteria are coated in vivo with immunoglobulin and complement. When the antibody is specific for crevicular bacteria, immunological interactions can be expected in the crevice. Our observations suggest that the anti-recombinant 40-kDa OMP antibody in concert with the crevicular complement may prevent P. gingivalis colonization r40-kDa OMP may contribute to the development of a local immunotherapy when applied to the crevice of a patient with P. gingivalis-related periodontitis which relates to susceptibility for certain systemic diseases such as diabetes mellitus, cardiovascular disease, and preterm labor.
Department of Biochemistry, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
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Saito
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Hayakawa
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H
Takiguchi
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Y
Abiko
D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000911:Antibodies, Monoclonal; D000915:Antibody Affinity; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology*; D004198:Disease Susceptibility; D006168:Guinea Pigs; D018922:HL-60 Cells; D006801:Humans; D008954:Models, Biological; D008970:Molecular Weight; D009504:Neutrophils / Q000276:immunology*; D009895:Opsonin Proteins / Q000502:physiology; D010518:Periodontitis / Q000276:immunology / Q000382:microbiology; D010587:Phagocytosis / Q000276:immunology; D016966:Porphyromonas gingivalis / Q000737:chemistry / Q000276:immunology*; D011817:Rabbits; D011863:Radioimmunoassay; D011994:Recombinant Proteins / Q000276:immunology
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D009895:Opsonin Proteins; D011994:Recombinant Proteins