Antigen 85C on Mycobacterium bovis, BCG and M. tuberculosis promotes monocyte-CR3-mediated uptake of microbeads coated with mycobacterial products.
The uptake in monocytes of monodispersed latex microbeads precoated with whole bacillus Calmette-Guérin (BCG) cells, Mycobacterium tuberculosis sonicate or culture fluid, or antigen (Ag) from the culture fluid was examined by microscopy. There was a significantly higher cell association of beads coated with whole BCG cells, the secreted 85C component of the Ag 85 complex or M. tuberculosis sonicate than of phosphate-buffered saline (PBS)-treated control beads. Antibodies (Ab) to Ag 85 inhibited the uptake of BCG- and Ag 85C-treated beads. A monoclonal antibody (mAb) to complement receptor type 3 (CR3), but not mAb to CR1, inhibited the uptake of Ag 85C-coated beads, indicating that the mycobacterial Ag-dependent uptake of particles was mediated via CR3 on the monocytes. This points to the existence of a ligand on Ag 85C which may promote monocyte uptake of M. bovis, BCG and M. tuberculosis.
Institute of Immunology and Rheumatology, National Hospital, University of Oslo, Norway.
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Hetland
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Wiker
D000911:Antibodies, Monoclonal / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001667:Binding, Competitive; D002478:Cells, Cultured; D003176:Complement C3 / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D016177:Macrophage-1 Antigen / Q000276:immunology*; D008863:Microspheres; D009000:Monocytes / Q000276:immunology*; D009163:Mycobacterium bovis / Q000276:immunology*; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D010587:Phagocytosis / Q000276:immunology
D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D003176:Complement C3; D007074:Immunoglobulin G; D016177:Macrophage-1 Antigen; C065036:antigen 85, Mycobacterium bovis