Phagocytic activity of polymorphonuclear leukocytes lavaged from the lungs of horses with clinically diagnosed chronic pulmonary disease.

The article discusses a study done to understand how different the activity of a certain type of white blood cell (polymorphonuclear leukocyte) is between healthy horses and horses with severe chronic lung disease (bronchiolitis) when exposed to two types of bacteria (Staphylococcus aureus). The cells from horses with the disease had decreased activity against one type of the bacteria but increased activity for the other, compared to their healthy counterparts. These differences were not found in blood samples from the same groups of horses.

Research Methodology and Findings

• The study was conducted on 28 horses, nine of which had been diagnosed with chronic inflammation of the lower airways.
• Polymorphonuclear cells (PMNs), a form of white blood cells that play a key role in the body’s immune system, were collected both from the bronchoalveolar lavage (a method of obtaining a sample of cells and debris from the airways and air sacs in the lung) and from peripheral blood of all the horses in the study.
• The phagocytic activity (the process by which cells engulf and destroy harmful substances or microorganisms) of these PMNs was then tested against two strains of Staphylococcus aureus bacteria, a common cause of lung infections.
• The first strain, Staph aureus Smith, was used after previous opsonization (a process by which bacteria are coated with antibodies making them more recognizable for white blood cells). The second strain, Staph aureus 305, was used without opsonization.
• It was found that PMNs lavaged from the horses with severe chronic bronchiolitis had decreased phagocytic activity against the opsonized Staph aureus Smith, but increased activity against the non-opsonized Staph aureus 305, compared to PMNs lavaged from healthy horses.
• No differences in the phagocytic activity of PMNs in the peripheral blood were observed between the clinically diseased horses and the healthy horses.

Significance of The Research

• The results from the study could be used to better understand the role of PMNs in the response of horses’ respiratory systems to bacterial infections and could provide useful insights into the immunology of equine chronic pulmonary conditions.
• The identification of the different activities based on opsonization could potentially lead to the development of new treatments targeting the PMNs’ response to bacteria.