Hemagglutinating properties of apolipophorin III from the hemolymph of Galleria mellonella larvae.

摘要

Larval haemolymph of Galleria mellonella caused aggregation of mammalian erythrocytes. The haemagglutinating agent was identified as an 18-kDa protein that did not react with lectins. The sequence of 81 amino acids in 3 protein fragments and the properties of the protein revealed that it was Galleria homologue of apolipophorin III (apoLp-III). ApoLp-III was found in great amounts in the haemolymph of larvae, pupae and adults, as well as in the moulting fluid. The haemagglutinating action of the whole haemolymph or the purified apoLp-III was independent of the presence of sugars in the medium. This indicated that it was not mediated by carbohydrates on the erythrocyte surface. The haemagglutination was inhibited at low pH (3.0), in the absence of calcium ions, and in the presence of certain bacterial lipopolysaccharides or their essential component, the 2-keto-3-deoxyoctonate-3-deoxyoctulosonic acid (KDO). It is suggested that interaction of apoLp-III with lipopolysaccharides in bacterial cell walls may play a role in insect immune reactions.