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

Nolwenn M. Dheilly*, Debra Birch, Sham V. Nair, David A. Raftos

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

The 185/333 proteins of sea urchins represent a family of highly variable immune response molecules with unknown functions. In this study, we show that 185/333 proteins are expressed by three cell types: amoebocytes, colourless spherule cells and gut-associated amoebocytes. A sub-population of amoebocytes express 185/333 proteins on the membranes of vesicles emanating from the trans-Golgi and which later fuse with the plasma membranes of the cells. The previously uncharacterized gut-associated amoebocytes also show a high level of 185/333 protein expression on their internal vesicles and plasma membranes. Colourless spherule cells contain 185/333 proteins within large spherules (specialized intracellular vesicles). In the presence of bacteria and yeast, the ultrastucture of colourless spherule cells changes and 185/333 proteins disappear. In contrast, 185/333 proteins were not found in the phagosomes of coelomocytes. The 185/333-positive gut amoebocytes were often associated with anuclear bodies, which appeared to incorporate material of microbial origin that was surrounded by 185/333 proteins. The association between 185/333 proteins on gut amoebocytes and anuclear bodies suggests that these proteins may be involved in the phagocytosis of microbes in the gut epithelium.

Original languageEnglish
Pages (from-to)861-869
Number of pages9
JournalImmunology and Cell Biology
Volume89
Issue number8
DOIs
Publication statusPublished - Nov 2011

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