Phagocytic amoebocyte sub populations in the perivisceral coelom of the sea urchinLytechinus variegatus (Lamarck, 1816)

Abstract

The echinoderms are deuterostomic animals with a nonspecific immune system similar to that of vertebrates. Among coelomocytes, phagocytic amoebocytes have a key role in the nonspecific immune response in sea urchin, being responsible for microorganisms elimination through phagocytosis and also for humoral secretions of a wide spectrum. Sub-populations of phagocytic amoebocytes (PA) have been previously described and two distinct sub populations in the oral (OR) and aboral (AB) regions of the perivisceral coelom of L.variegatus in the present study were found. In the OR there is a higher number of PA with higher phagocytic capacity after 30 minutes of incubation with yeast and higher percentage of intranuclear iron crystalloids. The germicide capacity under the fluorescence technique did not show any difference. SDS-PAGE analysis showed different protein patterns between coelomocytes of OR and AB. Gravitational force had no effect in PA distribution and no physical barrier was found in the perivisceral coelom. The other coelomocyte (vibratile cells, red spherulocytes and white spherulocytes) populations were not different in OR compared with AB in their distribution. Some aspects of the possible causes of the differences found for PA are discussed in the paper.

Changes in holothurian coelomocyte populations following immune stimulation with different molecular patterns

“…Foreign substances have been shown to induce phagocytosis in another sea cucumber species [46], as well as in the sea urchin [18, 47, 48] and the starfish larva [49] and adult [50]. Our results show that in H. glaberrima , other PAMPs (gram-positive bacteria and dsRNA) also activated the immune system.…”

Innate immune response in the sea urchin Echinometra lucunter (Echinodermata)

“…Our study identified granulocytes in peristomial membrane tissue in TEM after 2 weeks of time span. Thus, red spherule cells were involved with the inflammatory process in E. lucunter, different from other Brazilian sea urchin (L. variegatus) (Mangiaretta and Silva, 2001;Borges et al, 2005). These findings indicate potential differences in inflammatory response that require further investigation.…”

“…For these reasons, ferritin was chosen as an adequate marker for free amoebocytes in the perivisceral coelom of E. lucunter. Amoebocytes were later found (2 weeks) in the peristomial membrane of animals whose amoebocytes were marked by ferritin and the peristomial membrane was injected by India ink, thus showing the persistence of chronic inflammation in E. lucunter not established in L. variegatus (Mangiaretta and Silva, 2001;Borges et al, 2005).…”

Ultrastructural localization of highly variable 185/333 immune response proteins in the coelomocytes of the sea urchin, Heliocidaris erythrogramma

“…Other studies in different sea urchins also supported the existence of two distinct sub‐populations of amoebocytes. In Lytechinus Variegatus , Borges et al 22 found two distinct populations of amoebocytes in the aboral and oral region of the coelomic cavity. Density gradient centrifugation also separated two sub‐populations of amoebocytes in S. purpuratus and S. drobachiensis 21 , 23 .…”