Fcγ receptor-mediated phagocytosis pathway was involved in phagocytosis of mIgM + B lymphocytes from largemouth bass (Micropterus salmoides).

The potential for phagocytosis has been proven in teleost B cells, but the research on the regulatory mechanism of phagocytosis remains lacking. In this study, three largemouth bass (Micropterus salmoides) (15±5 g) were injected intraperitoneally with Nocardia seriolae (105 CFU/100 μL/fish) in vivo, and their spleen was collected respectively at 72 h post-infection for mRNA-seq. Following the de novo assembly of the paired-end reads, in all, 73,622 unigenes were obtained. The gene expression profiling revealed that 2,043 unigenes were differentially expressed post the Nocardia seriolae infection, including 1,285 up-regulated and 758 down-regulated unigenes (q-value < 0.05, log2FC > |2|) of which 181 genes were involved in the phagocytosis. The KEGG analysis demonstrated that 12 differentially expressed genes (DEGs) associated with phagocytosis were enriched in the Fcγ receptor-mediated phagocytosis signaling pathway. In vitro, the phagocytic ability of mIgM+ B lymphocytes was validated using IIFA and FACS, and the phagocytosis rates of the mIgM+ B lymphocytes incubated with a Lyn inhibitor had dropped from 18.533 ± 6.00% to 11.610 ± 4.236% compared with the unblocked group. These results suggested that the Fcγ receptor-mediated phagocytosis signaling pathway had participated in the phagocytosis of B cells, and provide us with further insight into the role of B cells in innate immunology. This article is protected by copyright. All rights reserved.