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Distribution of anti-CD68 (EBM11) immunoreactivity in formalin-fixed, paraffin-embedded bovine tissues
M R Ackermann1, B M DeBey, T J Stabel
1USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA.
Insights
The anti-CD68 (EBM11) antibody effectively identifies macrophages in various animal tissues, including cattle and pigs. This marker is valuable for diagnosing inflammatory conditions like bovine pneumonic pasteurellosis.
Area of Science:
- Veterinary Pathology
- Immunohistochemistry
- Cell Biology
Background:
- Macrophages play critical roles in tissue homeostasis and immune responses.
- Accurate identification of macrophages is essential for diagnosing inflammatory and infectious diseases in animals.
- The CD68 antigen is a well-established marker for cells of the monocyte-macrophage lineage.
Purpose of the Study:
- To evaluate the utility of a commercially available anti-human CD68 antibody (EBM11) for detecting macrophages in formalin-fixed, paraffin-embedded tissues from multiple animal species.
- To assess the antibody's effectiveness in identifying macrophages in both healthy and diseased states, specifically in bovine respiratory diseases.
Main Methods:
- Immunocytochemical staining using the anti-CD68 (EBM11) antibody on routinely processed tissues.
- Tissues were sourced from cattle, pigs, humans, rats, turkeys, dogs, and cats, encompassing both healthy and experimentally infected animals.
- Quantitative analysis of stained cells was performed, particularly in cases of bovine lung infection.
Main Results:
- The EBM11 antibody successfully labeled macrophages in healthy cattle, including alveolar and intravascular macrophages.
- In cattle infected with Pasteurella haemolytica, EBM11 stained the majority of alveolar macrophages and macrophages within septa, distinguishing them from neutrophils.
- Alveolar macrophages were also stained in pigs, but not in rats, turkeys, dogs, or cats, indicating species-specific reactivity. Macrophage aggregates were identified in infected cattle lymph nodes and intestines.
Conclusions:
- The anti-CD68 (EBM11) antibody is a reliable marker for macrophages in routinely processed bovine tissues, applicable in both normal and inflamed conditions.
- The findings support the use of EBM11 in diagnosing inflammatory conditions, such as bovine pneumonic pasteurellosis, and differentiating macrophages from neutrophils.
- The study highlights species-specific differences in CD68 expression, with notable reactivity in cattle and pigs.
Abstract:
A commercially acquired anti-human macrophage antibody (anti-CD68; EBM11) was used in an immunocytochemical technique to detect macrophages in formalin-fixed, paraffin-embedded tissues from cattle, pigs, humans, rats, turkeys, dogs, and cats. In healthy cattle, the antibody labeled alveolar macrophages, pulmonary intravascular cells (presumably intravascular macrophages), and macrophage-like cells in other tissues. In bovine lungs infected with Pasteurella haemolytica, EBM11 antibody labeled 95% of alveolar macrophages and macrophages within alveolar septa but only 0-2% of streaming or "oat" leukocytes. Alveolar macrophages were also stained by EBM11 in pigs but not in rats, turkeys, dogs, and cats. The antibody also stained macrophage aggregates in the mesenteric lymph nodes and intestinal lamina propria of Mycobacterium paratuberculosis-infected cattle. This study shows that the anti-CD68 (EBM11) antibody is a useful marker of macrophages in normal bovine tissues or tissues from areas of acute or chronic inflammation that have been routinely processed. The study also adds strength to the growing evidence suggesting that streaming leukocytes seen in pneumonic pasteurellosis are neutrophils.
