In humans, monocytes and macrophages (MØ) play a central role in immune regulation, tissue maintenance and pathogen control. In lower vertebrates, a few studies have been conducted on MØ like cells. In acute monocytic leukemia monocytic cells, as immature cells restrained in one of the phases of their ontogenesis, would offer the opportunity to rebuild an archaic condition helpful to understand the phylogenesis. Therefore, aim of this work was to characterize in the Rainbow trout (Salmo Gairdneri Richardson) MØ and compare them with acute leukemia monocytic cells. In the trout, MØ's morphology is similar to that of mammals. In particular, MØ possess an irregular embryoshaped nucleus occupying 2/3 of the cell, while the peripheral cytoplasmic profile is irregular with extroflexed plasmalemma and pseudopods. A morphological transition towards MØ is featured by a wavy hyaline classical membrane and an irregular and extroflexed surface. Some aspects of erythrophagocytosis represented a finding of great interest indicating that the hemocatheretic function could take place directly in circulation. This condition, also observed in human acute monocytic leukemia, suggests that the information to the erythrophagocytosis is restrained under physiological conditions. Non-specific esterases, which are positive in human MØ smear and MØ from human lymph node tissue, were also positive in the teleost studied but with a dysomogeneous pattern. Consequently non-specific esterase system is phylogenetically conserved. A lack of immune-reactivity with the anti-CD68 monoclonal antibody (MoAb) on smear and trout tissue sections was observed. On the contrary, strong positivity was detected on human lymph node sections. In trout, the presence of MØ and circulating MØ like cells exhibiting an erythrocatheretic function in the circulation would indicate a primordial function that has later been replaced by the liver and the spleen.
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis