IMMUNOCYTOCHEMICAL LOCALIZATION OF SECRETORY ACETYLCHOLINESTERASE OF THE PARASITIC NEMATODE NIPPOSTRONGYLUS-BRASILIENSIS

Various parasitic nematodes secrete acetylcholinesterase (AChE). In th is study, the localization of AChE in the nematode Nippostrongylus bra siliensis and the secretory forms of AChE in culture fluid were examin ed. A thiocholine method revealed that AChE activity was localized in the subventral glands, which have a secretory and excretory function v ia a duct connected to the excretory pore. By electron microscopy, ACh E activity was found mainly in the matrix of secretory granules, and s ometimes in the Golgi apparatus in the subventral gland cells. These r esults show that nematode AChE is produced and stored in the subventra l glands. Monoclonal antibodies against AChE of human erythrocytes or electric rays also bound to the nematode subventral gland, suggesting immuno-cross-reactivity of AChE among these species. When AChE activit y in the nematode excretory-secretory product was examined by SDS poly acrylamide gel electrophoresis combined with the thiocholine method, i ntense activity was demonstrated as a single band at 74 kDa. Immunoblo t analysis showed specific recognition of this molecule by IgE and IgG 1 antibodies, but not by IgG2a antibody, in nematode-infected rat sera . These results indicate that the nematode AChE molecule produced in a nd secreted from the subventral glands is antigenic for the production of IgE/IgG1 in host animals.