The white body is the main hemotopoietic organ of cephalopods. In this study, we have investigated the capacity of the octopus (Octopus vulgaris) white body cells to perform common cellular defense parameters known to be done by hemocytes of other mollusks such as phagocytosis of zymosan particles, respiratory burst activity and nitric oxide (NO) production. White body cells were capable of respiratory burst and NO production, however, they exhibited a low phagocytic response. Similar capabilities were observed in hemocytes withdrawn from the hemolymph. We have studied the effects of in vitro incubation with bacterial lipopolysacharide (LPS) or zymosan for 24 hours on these two functions. Incubation of the white body cells with zymosan, but not with LPS, resulted in a significantly increased respiratory burst activity and NO production. We have also investigated the capacity of circulating hemocytes and white body cells to increase their thymidine uptake (indicative of DNA synthesis) in response to LPs and phytothemaglutinin (PHA). In some animals, both mitogens induced a significant increase in thymidine uptake. If this thymidine uptake correlates with cell proliferation, this will be the first report of any proliferation of hemocytes in mollusks. In the hemolymph, we observed two different morphologies under the electron microscope, however, we cannot conclude that they correspond to two distinct cell types. Among white body cells different morphologies that may correspond to intermediate stoges were observed. All these findings represent a baseline for future studies to elucidate mechanisms of host defense in this mollusk.

6 páginas, 3 figuras

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