Morphological and flow cytometric characterization of leukocytes from the notothenioid teleosts Dissostichus eleginoides, Notothenia coriiceps, and Trematomus hansoni

To date, the adaptive immune response of the notothenioid fishes of the Sub- and High-Antarctic has received little attention. Here we characterize leukocyte preparations derived from head (pronephric) kidney, spleen, and intestine of three notothenioid species, Dissostichus eleginoides, Notothenia coriiceps, and Trematomus hansoni. Cells were collected from head kidney, spleen, and intestine, and were fixed in paraformaldehyde and analyzed by flow cytometry and optical microscopy. The three species displayed typical leukocyte populations composed of lymphocytes, granulocytes, monocytes/macrophages and thrombocytes with a peculiar organ distribution and peculiar flow cytometric patterns. This work represents the first characterization of cells involved in immune reactions in the investigated species.