Phagocytosis, invertebrates

Phagocytosis and encapsulation, in which pathogens are sequestered within several layers of cells, are the predominant cellular immune responses. Genetic and molecular studies have shown that bacterial products are recognized24 and transduced by host cells25 26 by similar pattern recognition receptors and signal transduction pathways in both vertebrates and invertebrates. 

The fundamental processes of immunity (pattern recognition, intracellular signaling, phagocytosis, cytotoxicity, clotting) remain largely similar and equally vulnerable to the effects of immunotoxicants whatever the invertebrate species. It could be argued that the constitutive nature of most invertebrate defense leaves them better equipped to... 

Phagocytosis is an important mechanism for the organism to rid itself of bacteria and pathogenic material, as well as cell debris and remnants of apoptosis. However, it can also provide a route for the uptake of pollutant particulate material. It is seen to be especially important in the incorporation of airborne particulate material, which often has serious health consequences (see Section 6.4). In terrestrial invertebrates, food is obtained either from particulate matter in the soil or from molecules dissolved in interstitial water. Most of these organisms have extracellular digestion, with nutrients and foreign material being absorbed by one or more of the routes available for transport across membranes, such as diffusion, channels or pinocytosis. There have been few studies to establish which route is taken. 

Reade, P. and Reade, E. (1976). Phagocytosis in invertebrates studies on the hemocytes of the clam Tridacna maxima, J. Invert. Pathol., 28, 281-290. 

Anderson, R.S. 1975. Phagocytosis by invertebrate cells in vitro Biochemical events and other characteristics compared with vertebrate phagocytic systems. In Invertebrate Immunity Mechanisms of Invertebrate Vector-Parasite Relations. Academic Press, San Francisco, CA, pp. 153-180. 

TRIPP M R (1992), Phagocytosis by hemocytes of the hard clam, Mercenaria merce-naria. J Invertebr Pathol, 59,222-227. 

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