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Destruction of cultured vascular endothelial cells and red blood cells by immune-activated polymorphonuclear
Abstract:
The cytotoxicity of human polymorphonuclear leukocytes (PMNs) against autologous red blood cells (RBC) and cultured vascular endothelial cells (EC) was investigated. PMNs were activated by phorbol myristate acetate (PMA) together with immune stimuli such as immune complexes and aggregated IgG. In the standard 51Cr-release assay, in which PMA concentration was 5 ng/ml and effector versus target ratio was 5, 76.7% and 34.2% specific 51Cr release was observed from RBC and EC, respectively. Significant levels of 51Cr were released, albeit to a lesser degree, when PMNs were stimulated by immune stimuli. Further experiments which employed various scavengers of oxygen radicals suggested that hydrogen peroxide was the most potent mediator of this cytotoxicity; the implications of these in vitro observations with the pathogenesis of immune vasculitis are of clinical interest.
Insights
Human white blood cells (polymorphonuclear leukocytes) can damage red blood cells and endothelial cells. Hydrogen peroxide is the primary cause of this damage, which may be relevant to immune vasculitis.
Area of Science:
- Immunology
- Cell Biology
- Pathology
Background:
- Human polymorphonuclear leukocytes (PMNs) play a crucial role in immune responses.
- The cytotoxic potential of PMNs against host cells is a significant area of research.
- Understanding PMN-mediated damage is vital for comprehending inflammatory and autoimmune diseases.
Purpose of the Study:
- To investigate the cytotoxic effects of activated human PMNs on autologous red blood cells (RBC) and vascular endothelial cells (EC).
- To identify the specific reactive oxygen species responsible for PMN-induced cytotoxicity.
- To explore the potential implications of these findings in the pathogenesis of immune vasculitis.
Main Methods:
- Activation of PMNs using phorbol myristate acetate (PMA) and immune stimuli (immune complexes, aggregated IgG).
- Quantification of cell damage using the standard 51Cr-release assay.
- Assessment of the role of oxygen radicals by employing various scavengers.
Main Results:
- Activated PMNs demonstrated significant cytotoxicity against both RBC (76.7% specific 51Cr release) and EC (34.2% specific 51Cr release) at a PMA concentration of 5 ng/ml and an effector-to-target ratio of 5.
- Immune stimuli also induced PMN cytotoxicity, though to a lesser extent than PMA alone.
- Experiments with oxygen radical scavengers indicated that hydrogen peroxide (H2O2) is the principal mediator of PMN-induced cytotoxicity.
Conclusions:
- Activated human PMNs exhibit potent cytotoxic activity against autologous RBC and EC.
- Hydrogen peroxide is identified as the primary cytotoxic mediator released by activated PMNs.
- These in vitro findings suggest a potential role for PMN-derived hydrogen peroxide in the pathogenesis of immune vasculitis, warranting further clinical investigation.