eoe sub articles

EoE Sub Articles

1. Culture, Differentiation, and Validation of HL-60 Cells
<ol>
	<li>Prepare HL-60 cell culture media composed of 500 mL Roswell Park Memorial Institute (RPMI) with L-glutamine and 50 mL heat-inactivated fetal bovine serum. Do not add antibiotics as this may affect the differentiation of the HL-60 cells.</li>
	<li>For propagation/maintenance of HL-60 cells, culture 5 x 106&#160;cells in 10 mL of HL-60 cell culture media in 75 cm2&#160;vented flasks at 37 &#176;C and 5% carbon diox...

assessment of opsonophagocytic killing activity against bacterial pathogens

Source: Paschall, A. V. et al., <a href="https://app.jove.com/v/59400">Opsonophagocytic Killing Assay to Assess Immunological Responses Against Bacterial Pathogens.</a>&#160;J. Vis. Exp.&#160;(2019)
The video shows an in vitro opsonophagocytic killing assay using a co-culture of human neutrophils with Streptococcus pneumoniae. Antibodies and complement proteins facilitate opsonization of the bacteria, enabling neutrophils to recognize and kill bacteria, showing successful neutrophil opsonophagocytic activity.

<img alt="Figure 1" src="/files/ftp_upload/21798/21798_Figure1.jpg" /> 
Figure 1: Validation of HL-60 cell differentiation via flow cytometry.&#160;Differentiated HL-60 cells were harvested, washed, and resuspended in 1 x 105&#160;cells/mL PBS. Cells were then aliquoted into 12 wells (100 &#181;L/well) in a 96-well plate. Cells were then stained with fluorescently conjugated anti-CD35, anti-CD71, annexin V, and propidium iodide. Unstained cells or cells st...

Assessment of Opsonophagocytic Killing Activity against Bacterial Pathogens

1. Culture, Differentiation, and Validation of HL-60 Cells

	Prepare HL-60 cell culture media composed of 500 mL Roswell Park Memorial Institute (RPMI) ...

Begin with a multi-well plate containing a Streptococcus pneumoniae suspension.
Introduce bacterial surface antigen-targeting antibodies, that interact with bacterial surface antigens. This coats the bacteria with antibodies, forming opsonized bacteria for immune recognition.
Seed the wells with human peripheral blood lymphocyte-derived neutrophils supplemented with rabbit serum containing complement proteins.
During incubation, the complement proteins such as C3b get deposited on the bacterial surface, leading to additional opsonin coating on the antibody-opsonized bacteria &#8212; enhancing bacterial recognition by neutrophils.
The specific surface receptors on the neutrophils interact with the opsonins on the bacteria, facilitating bacterial engulfment through phagocytosis.
Inside the phagosome, neutrophils degrade the engulfed bacteria, reducing the bacterial count in the buffer.
Post-incubation, spot the diluted co-culture solution onto a blood agar plate to allow individual bacteria to form colonies.
Compare the number of colonies in opsonin-treated bacteria to untreated bacteria.
Fewer colonies with opsonin treatment indicate higher bacterial killing, suggesting successful opsonophagocytic killing.

assessment-opsonophagocytic-killing-activity-against-bacterial

Research

JoVE Encyclopedia of Experiments

Immunology

Immunodiagnostics

Specialized Assays

Alveolar Macrophage Phagocytosis and Bacteria Clearance in Mice

Alveolar macrophages (AMs) guard the alveolar space of the lung. Phagocytosis by AMs plays a critical role in the defense against invading pathogens, the removal of dead cells or foreign particles, and in the resolution of inflammatory responses and tissue remodeling, processes that are mediated by various surface receptors of the AMs. Here, we report methods for the analysis of the phagocytic function of AMs using in vitro and in vivo assays and experimental strategies to differentiate between the pattern recognition receptor-, complement receptor-, and Fc gamma receptor-mediated phagocytosis. Finally, we discuss a method to establish and characterize a P. aeruginosa pneumonia model in mice to assess bacterial clearance in vivo. These assays represent the most common methods to evaluate AM functions and can also be used to study macrophage function and bacterial clearance in other organs.

Here we report common methods to analyze the phagocytic function of murine alveolar macrophages and bacterial clearance from the lung. These methods study in vitro phagocytosis of fluorescein isothiocyanate beads and in vivo phagocytosis of Pseudomonas aeruginosa Green Fluorescent Protein. We also describe a method for clearing P. aeruginosa in mice.

Alveolar macrophages (AMs) guard the alveolar space of the lung. Phagocytosis by AMs plays a critical role in the defense against invading pathogens, the ...

JoVE Journal

Immunology and Infection

A High-throughput Shigella-specific Bactericidal Assay

Serum bactericidal assays (SBAs) measure the functional activity of antibodies and have been used for many decades. SBAs directly measure antibody killing activity by assessing the ability of antibodies in serum to bind to bacteria and activate complement. This complement activation results in the lysis and killing of the target bacteria. These assays are valuable because they go beyond quantifying antibody production to elucidate the biological functions that these antibodies have, allowing researchers to study the role that antibodies may play in preventing infection. SBAs have been used to study immune responses for many human pathogens, but there is no widely accepted methodology for Shigella at present. Historically, SBAs have been very labor-intensive, requiring many time-consuming steps to accurately quantify surviving bacteria. This protocol describes a simple, robust, and high-throughput assay that measures functional antibodies specific for Shigella in serum in vitro. The method described here offers many advantages over traditional SBAs, including the use of frozen bacterial stocks, 96 well assay plates, a micro-culture system, and automated colony-counting. All of these modifications make this assay less labor-intensive and more high-throughput. This protocol is simpler and faster to perform than traditional SBAs while still using simple technologies and readily available reagents. The protocol has been successfully applied in multiple independent laboratories and the assay is robust and reproducible. The assay can be used to assess immune responses in pre-clinical as well as clinical studies. Quantifying shigellacidal antibody titers both before and after antigen exposure (either by immunization or infection) allows for a broader understanding of how functional antibody responses are generated and their contribution to protective immunity. The development of this standardized, well-characterized assay may greatly facilitate Shigella vaccine design.

A High-throughput Shigella-specific Bactericidal Assay

Here we present a protocol to measure Shigellacidal activity of antibodies in serum. Serum is mixed with bacteria and exogenous complement, incubated, and the reaction mixture is plated on agar plates. Viable bacteria form colonies which are counted, using an automated colony enumerator, and used to determine the bactericidal titer.

Serum bactericidal assays (SBAs) measure the functional activity of antibodies and have been used for many decades. SBAs directly measure antibody killing ...

Opsono-Adherence Assay to Evaluate Functional Antibodies in Vaccine Development Against Bacillus anthracis and Other Encapsulated Pathogens

The opsono-adherence assay is a functional assay that enumerates the attachment of bacterial pathogens to professional phagocytes. Because adherence is requisite to phagocytosis and killing, the assay is an alternative method to&#160;opsono-phagocytic killing assays. An advantage of the opsono-adherence&#160;assay is the option of using inactivated pathogens and mammalian cell lines, which allows standardization across multiple experiments. The use of an inactivated pathogen in the assay also facilitates work with biosafety level 3 infectious agents and other virulent pathogens. In our work, the opsono-adherence assay was used to assess the functional ability of antibodies, from sera of animals immunized with an anthrax capsule-based vaccine, to induce adherence of fixed Bacillus anthracis to a mouse macrophage cell line, RAW 264.7. Automated fluorescence microscopy was used to capture images of bacilli adhering to macrophages. Increased adherence was correlated with the presence of anti-capsule antibodies in the serum. Non-human primates that exhibited high serum anti-capsule antibody concentrations were protected from anthrax challenge. Thus, the opsono-adherence assay can be used to elucidate the biological functions of antigen specific antibodies in sera, to evaluate the efficacy of vaccine candidates and other therapeutics, and to serve as a possible correlate of immunity.&#160;&#160;&#160;&#160;&#160;&#160;

Opsono-Adherence Assay to Evaluate Functional Antibodies in Vaccine Development Against Bacillus anthracis and Other Encapsulated Pathogens

The opsono-adherence assay is an alternative method to the opsono-phagocytic killing assay to evaluate the opsonic functions of antibodies in vaccine development.

The opsono-adherence assay is a functional assay that enumerates the attachment of bacterial pathogens to professional phagocytes. Because adherence is ...

Assessment of Opsonophagocytic Killing Activity against Bacterial Pathogens

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