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Updated: Mar 6, 2026
A Method to Assess Fc-mediated Effector Functions Induced by Influenza Hemagglutinin Specific Antibodies
Published on: February 23, 2018
A novel flow cytometry-based assay for the quantification of antibody-dependent pneumococcal agglutination
Marrit N Habets1, Saskia van Selm1, Christa E van der Gaast-de Jongh1
1Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
Abstract:
The respiratory pathogen Streptococcus pneumoniae is a major cause of diseases such as otitis media, pneumonia, sepsis and meningitis. The first step towards infection is colonization of the nasopharynx. Recently, it was shown that agglutinating antibodies play an important role in the prevention of mucosal colonization with S. pneumoniae. Here, we present a novel method to quantify antibody-dependent pneumococcal agglutination in a high-throughput manner using flow cytometry. We found that the concentration of agglutinating antibodies against pneumococcal capsule are directly correlated with changes in the size and complexity of bacterial aggregates, as measured by flow cytometry and confirmed by light microscopy. Using the increase in size, we determined the agglutination index. The cutoff value was set by measuring a series of non-agglutinating antibodies. With this method, we show that not only anti-polysaccharide capsule antibodies are able to induce agglutination but that also anti-PspA protein antibodies have agglutinating capabilities. In conclusion, we have described and validated a novel method to quantify pneumococcal agglutination, which can be used to screen sera from murine or human vaccination studies, in a high-throughput manner.
Insights
Researchers developed a new high-throughput method to measure antibody-driven Streptococcus pneumoniae agglutination. This technique quantifies antibodies essential for preventing mucosal colonization, aiding vaccine development.
Area of Science:
- Immunology
- Microbiology
- Medical Technology
Background:
- * Streptococcus pneumoniae is a major respiratory pathogen causing severe diseases.
- * Nasopharyngeal colonization is the initial step in pneumococcal infection.
- * Agglutinating antibodies are crucial for preventing mucosal colonization by S. pneumoniae.
Purpose of the Study:
- * To develop and validate a novel high-throughput method for quantifying antibody-dependent pneumococcal agglutination.
- * To assess the correlation between antibody concentration and bacterial aggregate characteristics.
- * To determine the agglutinating capabilities of different antibody types against S. pneumoniae.
Main Methods:
- * Employed flow cytometry to measure changes in size and complexity of pneumococcal aggregates.
- * Confirmed flow cytometry findings using light microscopy.
- * Established an agglutination index based on the increase in aggregate size, defining a cutoff value using non-agglutinating antibodies.
Main Results:
- * Antibody concentration directly correlates with increased size and complexity of pneumococcal aggregates.
- * The developed method successfully quantified antibody-dependent pneumococcal agglutination.
- * Both anti-polysaccharide capsule and anti-PspA protein antibodies demonstrated agglutinating capabilities.
Conclusions:
- * A novel, high-throughput flow cytometry-based method for quantifying pneumococcal agglutination has been developed and validated.
- * This method allows for the screening of sera from vaccination studies to assess immune responses.
- * The findings highlight the agglutinating potential of antibodies against both pneumococcal capsule polysaccharides and PspA protein.
