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Adherence of erythrocytes to Mycoplasma pneumoniae
Abstract:
The human pathogen Mycoplasma pneumoniae adheres to a variety of cells, including erythrocytes. A hemadsorption technique was developed to quantitate adherence by photometric measurement of lysates of erythrocytes that attached to sheets of M. pneumoniae grown in cups of Linbro plates. Attachment of sheep erythrocytes (SE) increased with higher ionic strength, was unaffected by minor pH variations (6 to 9), and was blocked by anti-M. pneumoniae antiserum, but was not inhibited by a variety of sugars, amino acids, and bovine serum albumin. The reaction was time and temperature dependent. The temperature curve showed peaks at 14 and 28 degrees C with untreated SE but only one peak at about 38 degrees C with glutaraldehyde-treated SE. The temperature dependence indicated involvement of either metabolic or membrane activities in the binding process. Trypsin treatment of the M. pneumoniae sheet abolished adherence of SE but was only partially effective with human erythrocytes and noneffective with rabbit erythrocytes. The binding capacity of the mycoplasma cells for SE was restored by incubation in growth medium for 3 to 4 h; this restoration was inhibited by 10 mug of chloramphenicol per ml. Neuraminidase treatment of SE removed their attachment capacity but had no effect on attachment of rabbit erythrocytes and only a slight effect on attachment of human erythrocytes. Pretreatment of M. pneumoniae with neuraminic acid partially blocked the adherence of SE, whereas rabbit erythrocyte attachment was not affected. Attached SE could be detached by trypsin, but not by neuraminidase. For human and rabbit erythrocytes, the results suggest binding mechanisms other than the interaction between neuraminidase-sensitive receptors and protein-containing binding sites shown for SE.
Insights
Mycoplasma pneumoniae adheres to erythrocytes via temperature-dependent mechanisms. Sheep erythrocyte binding involves neuraminidase-sensitive receptors, unlike human and rabbit erythrocytes, suggesting varied adherence pathways.
Area of Science:
- Microbiology
- Cell Biology
- Pathogen-Host Interactions
Background:
- Mycoplasma pneumoniae is a human pathogen known to adhere to various host cells.
- Erythrocytes are among the cells that M. pneumoniae can attach to.
- Understanding M. pneumoniae adherence is crucial for elucidating infection mechanisms.
Purpose of the Study:
- To develop and utilize a quantitative hemadsorption assay for studying M. pneumoniae adherence to erythrocytes.
- To investigate the factors influencing M. pneumoniae attachment to different types of erythrocytes.
- To elucidate the specific molecular interactions involved in M. pneumoniae-erythrocyte binding.
Main Methods:
- Development of a photometric hemadsorption assay using M. pneumoniae grown in microplates and measuring erythrocyte lysate.
- Testing the effects of ionic strength, pH, temperature, and specific inhibitors (sugars, amino acids, BSA) on sheep erythrocyte (SE) adherence.
- Enzymatic treatments (trypsin, neuraminidase) of M. pneumoniae and erythrocytes to identify involved surface molecules.
- Investigating the role of metabolic activity and membrane components in the adherence process.
Main Results:
- Sheep erythrocyte adherence increased with ionic strength, was pH-independent (6-9), and blocked by specific antiserum.
- Adherence was time and temperature-dependent, with distinct temperature optima for untreated and glutaraldehyde-treated SE.
- Trypsin treatment of M. pneumoniae abolished SE adherence, while neuraminidase treatment of SE removed their attachment capacity.
- Neuraminidase-sensitive receptors and protein-containing binding sites were implicated in SE binding, but not for human or rabbit erythrocytes.
Conclusions:
- A novel hemadsorption assay quantifies M. pneumoniae adherence to erythrocytes.
- M. pneumoniae exhibits differential adherence mechanisms depending on the erythrocyte type.
- Sheep erythrocyte binding involves specific interactions with neuraminidase-sensitive receptors on erythrocytes and trypsin-sensitive sites on M. pneumoniae.
- Human and rabbit erythrocyte adherence likely involves alternative binding pathways distinct from those observed with sheep erythrocytes.