Abstract

Thrombocytes are nucleated hemostatic cells in teleost fish, known to function in coagulation and to play significant roles in immune regulation. However, the immune-related functions and characteristics of thrombocytes in turbot ( Scophthalmus maximus ) remain largely unexplored. In this study, we identified itgb3a as a highly expressed marker gene in turbot thrombocytes. Besides, we generated a polyclonal antibody targeting the conserved domain of ITGB3a and successfully isolated thrombocytes from turbot peripheral blood leukocytes. These isolated cells exhibited spherical or fusiform morphology with prominent pseudopodia and intracellular granules. Moreover, an in-depth reanalysis of single-cell transcriptomic data from our previous study uncovered a dynamic shift in the transcriptional profile of thrombocytes during infection, consistent with a change from innate immune responses to functions in metabolism and coagulation. Initially (3 dpi), their transcriptome was enriched for innate immune responses, and subsequently shifted towards metabolic regulation and coagulation homeostasis at 7–14 dpi. Furthermore, we demonstrated that proportion of turbot thrombocyte dynamically increased at 3 dpi, and observed the intracellular localization of bacteria within thrombocytes through in vitro assays with GFP-labeled Edwardsiella piscicida . Taken together, this study provides foundational insights into the functional characteristics of turbot thrombocytes during bacterial infection. Our findings offer valuable resources for advancing the understanding of fish thrombocyte biology and establish a basis for future exploration of potential therapeutic targets.