The effect on exogenous haemagglutinin on in vitro melanin deposition on microfilariae of Brugia pahangi in haemolymph of the mosquito, Armigeres subalbatus
Japanese Journal of Parasitology 365: 291-297
The encapsulation and melanization of microfilariae (Mf) of Brugia pahangi in haemolymph of the mosquito, Armigeres subalbatus, were studied in vitro. Heat-killed microfilariae (hk-Mf) were heavily melanized in both haemolymph samples and cell-free haemolymph samples of the mosquitoes of which the haemagglutinin titer had been increased by injection of Bacto-Phytohemagglutinin P (PHA-P). Heavy melanization of hk-Mf also occurred in haemolymph samples of the mosquitoes when PHA-P was added after collection of haemolymph. Induction of melanin deposition by PHA-P was inhibited by N-acetyl-D-galactosamine which is a haptenic sugar against PHA-P. Many lumps of melanin deposited on live Mf in cell-free haemolymph samples prepared from the mosquitoes injectd with PHA-P as densely as on hk-Mf. Haemagglutinin seems to be one of the mediators between parasitic nematodes and the prophenoloxidase systems of host insects.