Related Experiment Video

Updated: Aug 11, 2026

Fluorescence Microscopy Methods for Determining the Viability of Bacteria in Association with Mammalian Cells
07:23

Fluorescence Microscopy Methods for Determining the Viability of Bacteria in Association with Mammalian Cells

Published on: September 5, 2013

Inhibition of macrophage phagocytic activity by group A streptococcal cell walls

R J Smialowicz, J H Schwab

    Infection and Immunity
    |April 1, 1978
    PubMed

    Insights

    Group A streptococcal cell walls hinder macrophage phagocytosis of latex particles without reducing cell viability. Pre-incubation enhances this inhibitory effect, suggesting specific bacterial components impact immune cell function.

    Area of Science:

    • Immunology
    • Microbiology
    • Cell Biology

    Background:

    • Phagocytosis is a critical immune process by which macrophages engulf foreign particles.
    • Bacterial cell wall components can modulate host immune responses.

    Purpose of the Study:

    • To investigate the effect of streptococcal cell walls on macrophage phagocytosis of latex particles in vitro.
    • To determine if specific streptococcal groups or components influence this interaction.

    Main Methods:

    • Rat peritoneal macrophages were cultured in vitro.
    • Polystyrene latex particles were used as model targets for phagocytosis.
    • Group A and Group D streptococcal cell walls, along with peptidoglycan, were added to macrophage cultures.
    • Cell viability was assessed.
    • Phagocytosis was quantified.

    Main Results:

    • Group A streptococcal cell walls significantly inhibited the phagocytosis of latex particles by macrophages.
    • This inhibition occurred without a significant loss of macrophage viability.
    • Group D streptococcal cell walls showed minimal effect on phagocytosis.
    • Pre-incubation (12 hours) of macrophages with Group A variant cell walls or derived peptidoglycan enhanced their inhibitory effect on phagocytosis.

    Conclusions:

    • Group A streptococcal cell wall components actively interfere with macrophage phagocytosis.
    • The timing of exposure to bacterial cell wall components influences their impact on phagocytic activity.
    • Specific bacterial components, like those in Group A streptococci, may possess mechanisms to evade or modulate innate immune defenses.

    More Related Videos

    High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization09:22

    High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization

    Published on: November 27, 2014

    A Murine Model of Group B Streptococcus Vaginal Colonization10:19

    A Murine Model of Group B Streptococcus Vaginal Colonization

    Published on: November 16, 2016

    Related Concept Videos

    Defense Against Bacterial Pathogens01:31

    Defense Against Bacterial Pathogens

    The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
    Phagocytes
    Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
    Regulation of Bacterial Virulence01:28

    Regulation of Bacterial Virulence

    Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
    Streptococcal Pharyngitis01:27

    Streptococcal Pharyngitis

    Streptococcal pharyngitis, commonly known as “strep throat,” is an acute infection of the oropharyngeal tissues caused by the Gram‑positive Group A Streptococcus (Streptococcus pyogenes). Transmission occurs primarily through respiratory droplets expelled during coughing, sneezing, or talking.Mechanisms of Host Entry and Immune EvasionUpon entering the host, S. pyogenes adheres to the mucosal epithelial cells of the pharynx via surface proteins, notably lipoteichoic acid and the antiphagocytic...
    Inhibitors of Gram-positive Cell Wall Synthesis01:23

    Inhibitors of Gram-positive Cell Wall Synthesis

    Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
    Inhibitors of Bacterial Protein Synthesis01:25

    Inhibitors of Bacterial Protein Synthesis

    Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...