Vasoactive intestinal polypeptide-like immunoreactive tegumental cells in the digenean helminth Echinostoma liei:...

Immunocytochemical investigations were carried out on the tegument of the digenean platyhelminth Echinostoma liei. Tests with well-characterised antisera to mammalian vasoactive intestinal polypeptide (VIP) reveal a subpopulation of tegumental cells which contain material immunologically similar to VIP. Control experiments with antisera for a related peptide as well as absorption of primary antisera with VIP or secretin confirm the specificity of the reaction. Immunoreactive processes may be traced from the tegumental cells towards the distal cytoplasm of the tegument. Immunoreactivity is also concentrated in the outer layers of that cytoplasm. The finding of VIP-like immunoreactive material in peripheral nonneuronal, nonendocrine cells in this gastrointestinal parasite of mammals is discussed in terms of its implication for both parasite biology and host pathophysiology.