Head Kidney Cells Research Articles

Intermediate filaments in normal tissues and lymphomas of northern pike, Esox lucius L., from the Åland Islands of Finland

A battery of polyclonal and monoclonal antibodies directed against cytokeratins, desmin, vimentin, glial fibrillary acidic protein and neurofilament proteins of mammalian species was used to demonstrate intermediate filament (IF) expression in normal and lymphoma tissues of northern pike by indirect immunofluorescence microscopy. Frozen sections of pike intestine, skin, skeletal muscle, heart, liver, testis, head-, mid-, and posterior kidney and brain demonstrated IF in a manner which strengthens the idea that they are evolutionarily highly conserved. The results also confirm the IF-subclass specificities for different types of tissues, as noted by others in other species. Pike lymphoma cells showed morphological resemblance to head kidney cells; immunofluorescence microscopy and immunoblotting revealed vimentin expression, suggesting that the Åland pike lymphoma is a true mesenchymal neoplasm and is derived from haemic cells. The significance of these studies in relation to similar work with other species and to the possible use of IFs in the classification of normal and diseased tissues in fish is discussed.

Immunological classification of a pike lymphoma

Monoclonal and polyclonal antibodies against mammalian intermediate filament (IF) proteins were used to demonstrate IF expression in tissues and lymphoma tumors of northern pikes, Esox lucius L., from theÅland Islands of Finland by indirect immunofluorescence microscopy. Frozen sections of pike tissues demonstrated IFs in a manner confirming their evolutionary conservation and subclass specificity. Tumor cells showed morphological resemblance to head kidney cells and were positive for vimentin while negative for cytokeratin, desmin, neurofilament proteins, and glial fibrillary acidic protein. The results show that the neoplasm is a mesenchymal as opposed to an epithelial, muscle, neural, or glial tumor, and is probably hemic cell derived. A rabbit anti-pike IgM antiserum showed that up to 90% of mononuclear (MN) cells isolated on Ficoll-Isopaque gradients from peripheral blood, spleen and head kidney were surface- and cytoplasmic-immunoglobulin positive by indirect immunofluorescence, while a maximum of 5% of tumor cells were positive. A maximum of 5% of MN cells from hemic tissues exhibited rosettes when incubated with AET-treated sheep red blood cells; however, only 1% of cells in the tumor formed rosettes. Lymphocyte proliferation assays were performed on MN cells from hemic tissues and tumor using phytohemagglutinin P, concanavalin A, tuberculin purified protein derivative and lipopolysaccharide W in medium supplemented with fetal calf serum or autologous pike plasma. Proliferation indices in hemic tissues were similar in the groups. However, all proliferation indices in tissues were significantly higher than corresponding values in the tumor. These assays show that pike MN cells respond when stimulated by T and B cell mitogens, but that this reactivity is lacking in the tumor.

Lymphocyte heterogeneity in the trout, Salmo gairdneri, defined with monoclonal antibodies to IgM.

A monoclonal antibody to trout serum IgM was tested by immunofluorescence analysis with lymphocytes from thymus, spleen and head kidney. By visual examination, the antibody reacted with only a subpopulation of lymphocytes. The mean values +/- SE for positive cells were 5.2 +/- 2.3% in the thymus, 30.3 +/- 7.9% in the spleen and 12.4 +/- 3.0% in the head kidney. Flow cytofluorometric analysis revealed evidence of heterogeneity by size among the membrane IgM-positive cells of the head kidney and spleen. Depletion of head kidney cells positive for surface IgM by an immune affinity adherence technique of panning, using monoclonal anti-IgM, significantly reduced the mitogenic response to lipopolysaccharide but not to concanavalin A. It is suggested that this information supports the existence of distinct subpopulations of fish lymphocytes that may be homologous in certain respects to mammalian T and B type cells.