title: Quantitative assessment of phagocytic activity of hemocytes in the prawn, Penaeus merguiensis, by flow cytometric analysis.
abstract: BACKGROUND
  The blood cells of crustaceans are involved in phagocytosis of invading microorganisms, contributing to their defense mechanisms. In this study, phagocytic activity of hemocytes of the prawn, Penaeus merguiensis, was quantitated by means of flow cytometric analysis.
  
  
  METHODS
  This study was done in vitro. Hemolymph, which was extracted from prawns, was mixed with an equal volume of anticoagulant. Heat-killed Escherichia coli prestained with propidium iodide (PI) was then added. Hemocytes were fixed at various time intervals for flow cytometric analysis. This study was supplemented with electron micrographs using transmission electron microscopy (TEM), which showed three populations of hemocytes.
  
  
  RESULTS
  It was observed that those hemocytes that were more active engulfed and digested bacteria readily, thus having higher red fluorescence intensity. The phagocytic activity was expressed as fluorescence unit or engulfed E. coli number per hemocyte.
  
  
  CONCLUSIONS
  With this approach, the phagocytic and cellular activity of individual hemocyte populations could be studied quantitatively.
authors: Department of Microbiology, National University of Singapore, Singapore. micleeyk@nus.edu.sg
authors: Y K
authors: YK
authors: Lee
authors: B S
authors: BS
authors: Soh
authors: J H
authors: JH
authors: Wu
mesh_terms: D000818:Animals; D004926:Escherichia coli / Q000502:physiology; D005434:Flow Cytometry; D005453:Fluorescence; D006434:Hemocytes / Q000145:classification / Q000166:cytology* / Q000382:microbiology* / Q000648:ultrastructure; D006458:Hemolymph / Q000166:cytology; D008854:Microscopy, Electron; D033561:Penaeidae / Q000166:cytology* / Q000382:microbiology*; D010587:Phagocytosis; D011419:Propidium
chemical_list: D011419:Propidium