Related Experiment Video
Updated: Jun 19, 2026
11:12
Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs
Published on: March 9, 2013
THE RESISTANCE TO A SPECIFIC HEMOLYSIN OF HUMAN ERYTHROCYTES IN HEALTH AND DISEASE
1Biological Division of the Medical Laboratory of the Johns Hopkins Hospital.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Pigeon resistance to pneumococcus infection stems from their high body temperature, not just phagocytosis. Virulence involves both resisting immune cells and growing within the host.
Area of Science:
- Microbiology
- Immunology
- Pathogenesis
Background:
- Phagocytosis is a key immune defense against bacterial infections.
- Bacterial virulence is multifactorial, involving host defenses evasion and replication.
- Animal models are crucial for understanding infectious disease dynamics.
Purpose of the Study:
- To investigate the role of phagocytosis in pneumococcal infections in vitro and in vivo.
- To determine factors contributing to pneumococcal virulence.
- To compare the biological response to pneumococcus in pigeons and mice.
Main Methods:
- In vitro phagocytosis assays of pneumococci.
- In vivo infection models using mice and pigeons.
- Comparative analysis of host-pathogen interactions.
Main Results:
- In vitro and in vivo pneumococcal phagocytosis correlated.
- Pneumococcal virulence depends on both resistance to phagocytosis and host replication.
- Pigeons and mice exhibit similar biological reactions to pneumococcus.
- Pigeon resistance is linked to their higher body temperature.
Conclusions:
- Host temperature significantly impacts resistance to bacterial infections.
- Phagocytosis and host replication are critical determinants of bacterial virulence.
- Pigeons possess natural immunity to pneumococcus due to thermoregulation.
Related Concept Videos
01:27Disorders of Erythrocytes
Disorders of erythrocytes, or red blood cells (RBCs), include a range of conditions affecting their number, shape, or function.
Erythrocyte disorders can be broadly categorized into two main types: anemic and polycythemic conditions.
A low oxygen-carrying capacity of the blood due to the loss, lower production, or destruction of erythrocytes is termed anemia. Hemorrhagic anemia, for example, occurs when bleeding from an external wound or internal ulcer reduces erythrocyte counts.
On the other...
Erythrocyte disorders can be broadly categorized into two main types: anemic and polycythemic conditions.
A low oxygen-carrying capacity of the blood due to the loss, lower production, or destruction of erythrocytes is termed anemia. Hemorrhagic anemia, for example, occurs when bleeding from an external wound or internal ulcer reduces erythrocyte counts.
On the other...
01:19Rh Blood Group
The Rhesus (Rh) antigen is crucial in determining blood groups and ensuring compatibility during blood transfusions.
01:01Hypersensitivity Reactions: Cytolytic Reactions
Type II hypersensitivity involves IgG and IgM antibodies targeting cell surface antigens, leading to cell destruction. This can occur through complement activation, antibody-dependent cell-mediated cytotoxicity (ADCC), or acting as opsonins for phagocytosis. When excessive, these reactions cause significant tissue damage.Drug-induced hemolytic anemia is a common example, where drugs like penicillin or cephalosporins bind to red blood cells, forming drug-protein complexes. These complexes...
01:14Erythropoiesis
Red blood cells (RBCs) transport oxygen to all body tissues. These cells survive only for 120 days and then need to be replenished. Erythropoiesis is the process of RBC production. In healthy individuals, erythropoiesis ensures all tissues are amply supplied with oxygen. In addition, blood loss due to injury leads to a drop in the physiological oxygen level that will cause erythropoiesis. Any defect in erythropoiesis leads to several physiological disorders, including thalassemia, anemia, and...
01:22Lifecycle of Erythrocytes
Erythrocytes, also known as red blood cells, constantly move through blood capillaries. As a result, they damage their plasma membrane due to the continuous friction. Typically, after 100 to 120 days, erythrocytes become rigid and fragile as they wear out. As they pass through small vessels in the spleen and liver, they can get trapped and break apart into fragments.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
01:24Factors Affecting Erythropoiesis
The cardiovascular system regulates the number of erythrocytes in the bloodstream to ensure optimal oxygen transport. It also prevents over-proliferation of these cells, which helps to maintain blood viscosity and flow rate.
Several factors influence the erythrocyte production rate, with tissue oxygen level being among the most critical. Intense exercise or high altitudes can cause tissue hypoxia, which triggers the kidneys to release more erythropoietin (EPO) into the bloodstream.
EPO then...
Several factors influence the erythrocyte production rate, with tissue oxygen level being among the most critical. Intense exercise or high altitudes can cause tissue hypoxia, which triggers the kidneys to release more erythropoietin (EPO) into the bloodstream.
EPO then...