The generation and characterisation of anti-insect blood cell monoclonal antibodies

Abstract

ABSTRACT A number of monoclonal antibodies have been raised against the haemocytes (blood cells) of two insect species: namely, the wax moth, Galleria mellonella and a species of cockroach, Blaberus discoidalis. In the case of the wax moth, two groups of monoclonal antibodies were raised. One group, designated GM1 to GM28, identified only one type of blood cell, namely the gran-ular cell. All 28 monoclonal antibodies recognised a 90 kDa protein as shown by western blotting. The second group of monoclonal antibodies, designated GallPG1 to GallPG20, recognised all the haemocyte types of G. mel -lonella, including the granular cells, prohaemocytes, plasmatocytes, spherule cells and oenocytoids. These latter monoclonal antibodies all identified a protein of 35 kDa when tested by western blotting. All monoclonal antibodies against G. mellonella haemocytes were highly specific for wax moth haemocytes and did not cross-react with any other lepidopteran, orthopteran or dic-tyopteran haemocytes tested. With the cockroach, B. discoidalis, there were two main sets of monoclonal anti-bodies produced against the haemocytes; however, none was specific for any of the three haemocyte types found in this species, namely, the granular cells, plasmatocytes and prohaemocytes. One group of Blaberus monoclonal antibodies, termed BlabMem1 to BlabMem19, labelled the cell surface and cytoplasm of the plasmatocytes, pro-haemocytes and granular cells. These monoclonal anti-bodies all recognised a protein of approximately 60 kDa. The second group of monoclonal antibodies, designated BlabGr1 to BlabGr31, labelled the granular inclusions of all haemocyte types. The monoclonal antibodies against the Blaberus haemocytes did cross-react with the blood cells of some closely related species of cockroach, but not with the haemocytes of any of the lepidopterans or orthopterans tested. Initial experiments showed that exposure of Galleria haemocytes to the monoclonal anti-bodies specific for the 90 kDa protein (GM1 to GM28), significantly reduced the ability of these cells to attach to bacteria in vitro. These results suggest that this pro-tein plays a central role in the cellular defence reactions of insects and that these monoclonal antibodies should be extremely useful in further investigating its func-tional significance.