Hemocytes and hemocytic responses in the mole crab Emerita emeritus (Linnaeus 1767).

The mole crab, Emerita emeritus, collected from the sandy shores of a Chennai beach, was investigated for cellular immune responses based on the morphology and defensive reactions of the circulating haemocytes. Three haemocyte morphotypes were identified using light and electron microscopy, and separated in a discontinuous percoll gradient. A phagocytosis study using human B erythrocyte as a target cell under phase-contrast optics showed that granular and semi-granular haemocytes were phagocytic, and this response was enhanced by using serum (opsonin)-coated human B erythrocyte in unfractionated and fractionated haemocytes. Observation of TEM image of phagocytosis revealed that the initial recognition and binding of the target cell was restricted to granular and semigranular haemocytes, which were lacking with hyaline cells. However, the encapsulation of DEAE Sepharose CL 6B beads, either untreated or coated with serum (opsonin), was restricted to hyaline cells. This suggests the occurrence of two cell lines in haemocytes, based on the differences observed in the response of haemocytes to bind target cells for phagocytosis or encapsulation. The present study also differentiated the activation of PO in the plasma, serum, and haemocyte lysate supernatant (HLS).