Surface Markers on the Haemocytes of the Freshwater SnailPlanorbarius corneus(L.) (Gastropoda, Pulmonata)

Trichobilharzia ocellata in Lymnaea stagnalis: a flow cytometric approach to study its effects on hemocytes

Flow cytometric analysis was performed on hemocytes in suspension derived from individual Lymnaea stagnalis. The distribution of cell sizes within the hemocyte population was comparable in all 40 specimens studied. The size distribution of circulating hemocytes is unimodal and continuous, with no discrete subpopulations, and is not affected by age or by infection with Trichobilharzia ocellata. Flow cytometry proved to be a very useful technique in analysis of hemocyte populations in snails and anti-hemocyte monoclonal antibodies can be employed in these studies. The use of individual instead of pooled hemolymph samples in studying hemocyte populations of molluscs is stressed.

Cytotoxicity and immunocyte markers in cells from the freshwater snail Planorbarius corneus (L.) (Gastropoda pulmonata): implications for the evolution of natural killer cells

The hypothesis that natural killer (NK) cells represent an important form of cell recognition and cytotoxicity leads to the prediction that NK-like activity should be preserved throughout phylogenetic development. This was tested in the invertebrate Planorbarius corneus. Two types of cells can be identified and separated from the hemolymph of this mollusc, i.e. glass-adherent macrophage-like spreading hemocytes (SH) and nonadherent round hemocytes (RH). Only RH are able to lyse the K-562 human target cell line in a short-term NK cytotoxicity test. This NK-like activity, severely reduced after 18 h incubation at 24 degrees C, is preserved by human recombinant interleukin 2. A further analysis of P. corneus hemocytes has been performed by using several mouse anti-human monoclonal antibodies and cytofluorimetric analysis. Unexpectedly, both SH and RH react with several monoclonal antibodies, including those directed against epitopes typical of mammalian NK cells and cell adhesion molecules. On the whole, these data support the hypothesis that a primitive NK-like activity appeared early in evolution and is not shared by phagocytic cells.

Immunodetection of haemocyte subpopulations by N-acetylmuramic acid antibody in Planorbarius corneus (L.) (Gastropoda, Pulmonata)

The cell subpopulations in the haemolymph of Planorbarius corneus were distinguished by means of flow cytometry. An antibody against N-acetylmuramic acid was prepared and used as a cellular marker to recognize the cell types forming the subpopulations. The spreading haemocytes showed a positive reaction for anti-N-acetylmuramic acid; round haemocytes gave a negative reaction.