BACKGROUND: The innate immune response constitutes the first line of defense against invading pathogens and consists of a variety of immune defense mechanisms including active endocytosis by macrophages and granulocytes. Endocytosis can be used as a reliable measure of selective and non-selective mechanisms of antigen uptake in the early phase of an immune response. Numerous assays have been developed to measure this response in a variety of mammalian and fish species. The small size of the zebrafish has prevented the large-scale collection of monocytes/macrophages and granulocytes for these endocytic assays. METHODOLOGY/PRINCIPAL FINDINGS: Pooled zebrafish kidney hematopoietic tissues were used as a source of phagocytic cells for flow-cytometry based endocytic assays. FITC-Dextran, Lucifer Yellow and FITC-Edwardsiella ictaluri were used to evaluate selective and non-selective mechanisms of uptake in zebrafish phagocytes. CONCLUSIONS/SIGNIFICANCE: Zebrafish kidney phagocytes characterized as monocytes/macrophages, neutrophils and lymphocytes utilize macropinocytosis and Ca(2+)-dependant endocytosis mechanisms of antigen uptake. These cells do not appear to utilize a mannose receptor. Heat-killed Edwardsiella ictaluri induces cytoskeletal interactions for internalization in zebrafish kidney monocytes/macrophages and granulocytes. The proposed method is easy to implement and should prove especially useful in immunological, toxicological and epidemiological research.
Public Library of Science
College of Veterinary Medicine
Department of Basic Sciences
Animals, Antigens, Antigens: metabolism, Calcium, Calcium: metabolism, Cell Surface, Cell Surface: metabolism, C-Type, C-Type: metabolism, Edwardsiella ictaluri, Edwardsiella ictaluri: metabolism, Endocytosis, Endocytosis: physiology, Flow Cytometry, Fluorescein-5-isothiocyanate, Kidney, Kidney: cytology, Lectins, Mannose-Binding Lectins, Mannose-Binding Lectins: metabolism, Phagocytes, Phagocytes: metabolism, Pinocytosis, Receptors, Zebrafish, Zebrafish: metabolism
Hohn, Claudia; Lee, Sang-Ryul; Pinchuk, Lesya M.; and Petrie-Hanson, Lora, "Zebrafish kidney phagocytes utilize macropinocytosis and Ca+-dependent endocytic mechanisms." (2009). CVM Publications. 14.