ИСТИНА

Several substances presented in the tapeworms’ larvae can modulate the host immunity: PG E2; PG D2; GABA, as well as serotonin (Biserova et al, 2011; 2014; Biserova, Kutyrev, 2014 a, b; Kutyrev et al, 2017; Kutyrev, 2017). Analysis of excretory-secretory products of metacestodes reveals potential suppressors of dendritic cell functions in the hosts (Vendelova et al, 2016). The aim of our research was detect cellular sources of immunomodulatory molecules in two cestodes species Diphyllobothrium dendriticum and Ligula interrupta. For the first time in L. interrupta plerocercoids we identified immunoreactions (IR) to prostaglandins E2 and D2 in different types of cells and neuroactive substances as GABA, serotonin and FMRF-amide in the neurons. In D. dendriticum plerocercoids we found the PGE2 IR in small neurons belonging to the main cords and commissures. In both species the PGE2-IR partly coincided with α-tubulin-IR and it was found in the apical terminals of the frontal glands and free nerve endings. PGD2-IR occurred in the muscle fibers and coincided with phalloidin TRITC staining of the F-actin in the muscles. Both PGE2 and PGD2 were found in the flame cells of the excretory system of these tapeworms. We proved that parasites excrete the prostaglandins E2 and D2 in response to the host blood serum. By ultrastructural investigations, we found number of cell sources of excretory-secretory products: neurons and free nerve endings, frontal glands and tegument. This work was supported by the RFBR (#15-04-02645; 16-04-01213)