Study of Macrophages in Common Carp (Cyprinus Carpio) With Special Emphasis on Gill and Swim Bladder: Biomarkers for Risk Assessment of Pollution

ABSTRACT Macrophage aggregates (MAs) are found in tissues of teleost fishes, including spleen, head kidney, and liver, in relation to inflammation. Many factors like age, pollution, infectious diseases are known to affect the formation, accumulation, and proliferation of macrophages in teleosts. Numerous studies have shown an increase in number and size of macrophage aggregates (MAs) in fish collected at contaminated sites. The present work has focused on morphological studies on macrophages in the head kidney, gill tissue, and swim bladder (SB) of common carp (Cyprinus carpio). Alive fish samples were collected from local markets, and tissues from head kidney, gills were removed. Cells were isolated. The adherent macrophages were fixed by methanol and stained by Giemsa and neutral red. The exudate from swim bladder was collected for studying macrophage cells from the inflammation. The present work showed Giemsa and neutral red stained free macrophages or macrophage aggregates on glass slides. The tendency of cell aggregation reflects cell to cell adhesiveness, which serving as a marker for macrophage activation. More macrophage aggregation or accumulation indicates more macrophage activation, sometimes leads to inflammation. Therefore, studies on macrophages of common carp (Cyprinus carpio) may be used as the markers of fish health and aquatic pollution.