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Immunoglobulins to group A streptococcal surface molecules decrease adherence to and invasion of human pharyngeal
U Fluckiger1, K F Jones, V A Fischetti
1Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York, New York 10021, USA.
Infection and Immunity
|March 6, 1998
Summary
Secretory immunoglobulin A (sIgA) antibodies prevent Streptococcus pyogenes adherence to throat cells, while M protein-specific IgG antibodies inhibit bacterial invasion. These findings highlight the roles of antibodies in combating streptococcal infections.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Group A Streptococcus (Streptococcus pyogenes) M protein is a key virulence factor in initial infection stages.
- Acute pharyngitis, a common infection, is caused by Streptococcus pyogenes.
- Understanding antibody roles in preventing streptococcal adherence and internalization to pharyngeal cells is crucial.
Purpose of the Study:
- To investigate the inhibitory effects of secretory immunoglobulin A (sIgA) and immunoglobulin G (IgG) on Streptococcus pyogenes adherence and internalization to human pharyngeal cells.
- To determine the specific roles of whole sIgA, M6 protein-specific sIgA, and M6 protein-specific serum IgG in these processes.
Main Methods:
- Utilized Streptococcus pyogenes strains: D471 (M protein-positive) and JRS75 (M protein-negative).
- Tested purified whole sIgA, M6 protein-specific sIgA, and M6 protein-specific IgG for their effects on streptococcal adherence and internalization to cultured human pharyngeal cells.
- Employed sIgA preabsorbed with M protein to assess specificity.
Main Results:
- Purified whole sIgA and M6 protein-specific sIgA significantly reduced streptococcal adherence to pharyngeal cells.
- sIgA preabsorbed with M protein also decreased bacterial adherence, indicating M protein's role in this interaction.
- M6 protein-specific IgG antibodies did not affect bacterial attachment but significantly reduced internalization.
Conclusions:
- Secretory IgA plays a critical role in preventing Streptococcus pyogenes infection at mucosal surfaces by inhibiting bacterial adherence.
- M protein-specific IgG antibodies are important for blocking bacterial invasion by targeting specific epitopes involved in internalization.