Phagocytosis in the colonial ascidian Botryllus schlosseri.

Phagocytosis by Botryllus schlosseri hemocytes is influenced by temperature, pH, concentration, and physicochemical properties of the test particles and requires Ca2+ or Mg2+ ions to occur. Phagocytes recognize glucosyl or mannosyl residues on the surface of yeast cells, and a respiratory burst is associated with phagocytosis, as indicated by increased superoxide production. Factors that enhance phagocytosis of yeast, sheep red blood cells, and latex beads and reduce the uptake of yeast and sheep erythrocytes are present in the plasma.