Abstract: To study the immune-like cells during the development of Dictyostelium discoideum,fluorescent dye Ethidium bromide (EB) was used as surrogates for the environment toxins that Dictyostelium might encounter in the soil. With the help of fluorescence microscopy, only rufous mound cells were visualized. Positioning of nucleus by Hoechst33342 was to confirm that EB was phagocytosed into the intracellular. During the slug stage, the florescent dye EB displayed highly accumulation within a small subset cells and eventually was found in the abandoned sheath as the slug continued to migrate.The special kind cells in the slug had the ability to sequester EB. The results from flow cytometry showed that the immune-like cells existed in pre-stalk cells, suggesting the simple immune-like cells present in Dictyostelium discoideum, which is the foundation to futher study the occurrence and development of immunity system.

Key words: Dictyostelium discoideum, slug, immune-like cells, Ethidium bromide(EB)