108.2 Saturday, Jan. 7 In vitro cell-cell co-operation during cellular immune functions in the edible marine crab Scylla serrata NALINI PADMANABHAN, M; KARPAGAM UNIVERSITY, COIMBATORE, INDIA firstname.lastname@example.org
Hemolymph coagulation of Scylla serrata was completely prevented by use of a suitable anticoagulant. This enabled for obtaining the hemocytes in native form together with their inherent ability to attach and spread well on glass surface. Three distinct hemocyte morphotypes namely hyaline (H: 43%), semigranular (SG: 35%) and granular (G: 22%) were identified based on the degree of cytoplasmic granulation. These hemocyte morphotypes were successfully separated by a single-step discontinuous density gradient of Percoll. Irrespective of the morphotypes, they contained various immune molecules and displayed the two vital cellular immune responses namely, phagocytosis and encapsulation at varying levels. Plasma enhanced the phagocytic activity of SG and G cells whereas it facilitated and intensified the encapsulation response of all the cell types. Soluble factors derived from the hemocytes also modulated the phagocytic and encapsulation responses, wherein soluble factors derived from SG and G cells exerted opsonophagocytic effect only on G cells. In encapsulation assays, the hemocyte-derived promoting factor specifically acted on H cells, while the inhibiting factor selectively interacted with G cells. Thus the findings of experimental studies performed using pure populations of hemocytes demonstrated the existence of interactive events between specific hemocyte types during cellular immuno-defense reactions. Therefore, it could be envisaged that such co-operative cellular interactions are vital for potentiation as well as regulation of hemocyte-mediated immune functions in crustaceans.