An analysis of the structural and functional similarities of insect hemocytes and mammalian phagocytes

Abstract

The insect immune response demonstrates a number of structural and functional similarities to the innate immune system of mammals. As a result of these conserved features insects have become popular choices for evaluating the virulence of microbial pathogens or for assessing the efficacy of antimicrobial agents and give results which are comparable to those that can be obtained using mammals. Analysis of the cellular component of the insect and mammalian immune systems demonstrates many similarities. Insect hemocytes recognize pathogens and phagocytose material in a similar manner to neutrophils. The killing of ingested microbes is achieved in both cell types by the production of superoxide and by the release of enzymes in the process of degranulation. Insect hemocytes and mammalian neutrophils are sensitive to the same inhibitors. This review highlights the strong similarities between the phagocytic cells of both groups of animals and demonstrates the potential benefits of using selected insects as in vivo screening systems.

Assessment of in vivo antimicrobial activity of the carbene silver(I) acetate derivative SBC3 using Galleria mellonella larvae

“…The insect immune system shows many similarities to the innate immune system of mammals (Kavanagh and Reeves 2004;Browne et al 2013) and, as a consequence, insects have been used as models to measure the virulence of microbial pathogens (Fuchs and Mylonakis 2006) and to evaluate the potency of antimicrobial drugs (Hamamoto et al 2004;Rowan et al 2009) and give results consistent with those that can be obtained using mammals (Jander et al 2000;Brennan et al 2002). A number of insect species can be employed for evaluating the in vivo activity of novel antimicrobial drugs (Kavanagh and Fallon 2010) and larvae of the Greater Wax Moth, Galleria mellonella are now widely used in this capacity (Kelly and Kavanagh 2011;Rowan et al 2009;Desbois and Coote 2012).…”

Cellular immune response of the Asian corn borer, Ostrinia furnacalis (Lepidoptera: Pyralidae), to infection by the entomopathogenic fungus, Beauveria bassiana

“…The density of haemocytes in the haemolymph varies during the life of the insect and also in response to the challenge of pathogens (Bergin et al, 2003;Browne et al, 2013). In this study, the number of total free haemocytes per larva decreased signifi cantly 0.5, 24, and 36 h after the injection of B. bassiana conidia (Fig.…”

“…We identifi ed fi ve types of haemocytes in Asian corn borer haemolymph: granulocytes, oenocytoids, plasmatocytes, prohaemocytes, and spherulocytes, which are commonly found in other insects (Ling et al, 2005;Browne et al, 2013;Vogelweith et al, 2016). Hu et al (2003) also identifi ed these fi ve haemocyte types in O. furnacalis larvae under phase contrast microscopy and transmission electron microscopy.…”

“…Unlike phagocytosis, nodulation and encapsulation result in the formation of a multilayered, overlapping sheaths of haemocytes around the invader. In Lepidoptera, only granulocytes and plasmatocytes are reported to be involved in these three processes (Browne et al, 2013).…”

“…Circulating haemocytes (insect blood cells) play critical roles in insect cellular immune responses. There are at least fi ve types of haemocytes commonly found in insects: granulocytes (= granular cells), oenocytoids, plasmatocytes, prohaemocytes, and spherulocytes (= spherule cells) (Browne et al, 2013). In lepidopteran larvae, granulocytes and plasmatocytes together usually comprise > 50% of the total haemocytes (Lackie, 1983;Strand & Pech, 1995).…”