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Human salivary aggregation in Streptococcus intermedius type g strains: relationship with IgA
1Department of Preventive Dentistry, Kagoshima University Dental School, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan. yamatai@dentb.hal.kagoshima-u.ac.jp
FEMS Immunology and Medical Microbiology
|May 18, 2004
Summary
Human saliva contains Immunoglobulin A (IgA) that causes Streptococcus intermedius K1K bacteria to aggregate. This calcium-dependent immunoreaction is crucial for eliminating bacteria and preventing infection.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Bacterial aggregation is a key mechanism for clearing pathogens from the human body.
- Streptococcus intermedius K1K exhibits aggregation in human saliva, necessitating identification of the responsible factor.
Purpose of the Study:
- To identify the salivary agglutinin responsible for Streptococcus intermedius K1K aggregation.
- To characterize the nature of this bacterial aggregation and its dependence on specific factors.
Main Methods:
- Purification of salivary agglutinin using ion-exchange and gel filtration chromatography.
- Characterization of the purified agglutinin via electrophoresis and immunological techniques.
- Assessing aggregation inhibition using specific antisera and evaluating calcium dependency.
Main Results:
- The salivary agglutinin was identified as Immunoglobulin A (IgA).
- Aggregation was completely inhibited by antisera against human alpha chain and whole saliva, but not micro chain or IgG.
- Bacterial aggregation was found to be dependent on the presence of calcium ions.
- Significant variations in aggregation activity were observed among saliva samples from different individuals.
Conclusions:
- Bacterial aggregation of Streptococcus intermedius K1K in saliva is mediated by an immunoreaction involving salivary IgA and calcium-dependent bacterial surface antigens.
- This finding highlights the role of IgA in innate immunity against specific bacterial infections.