The Influence of Secretory Products of Morula Cells on Phagocytes of the Holothurian Eupentacta fraudatrix (Djakonov et Baranova, 1958) (Sclerodactylidae: Dendrochirotida)

Abstract

The influence of humoral products of morula cells on apoptosis, the concentration of cytokinin-like compounds, and expression of cell-surface receptors specific to plant lectins from Arachis hypogaea, Glycine max, and concanavalin A (Con A) were studied in two types of phagocytes (P1 and P2) of the Far Eastern sea cucumber Eupentacta fraudatrix (Djakonov et Baranova, 1958). Our data show that morula cell supernatant reduced the level of apoptosis and concentration of interleukin-1α-like factors (IL-1α-LF) in P1 phagocytes, while it increased them in P2 phagocytes. We hypothesize that an increase in IL-1α-LF concentration stimulates apoptosis in E. fraudatrix P2 cells under the effect of treatment with morula cell supernatant. Moreover, opposite changes in apoptosis levels in P1 and P2 phagocytes in response to morula cell supernatant correlate with the expression of receptors of different types: N-acetyl-D-galactosamine- and β-D-galactose-containing receptors in P1 phagocytes and α-D-mannose-containing receptors in P2 phagocytes. Taken together, our results support the idea of differential roles of P1 and P2 phagocytes in the holothurian immune response. The study suggests that the differences in the binding of lectins to P1 and P2 cell-surface receptors is a distinctive feature and can be used in phenotyping of these immunocytes.