Single-cell RNA-seq reveals different subsets of non-specific cytotoxic cells in teleost.

Non-specific cytotoxic cells (NCC) are important cytotoxic leukocytes in teleost immune system. However, the NCC subsets have not been clarified. Thus, we create a comprehensive cell map of ~24,062 head kidney-derived leukocytes from Nile tilapia post poly I:C stimulation using single-cell RNA sequencing (scRNA-seq). Based on cell heterogeneity and known markers, the cells were classified into four cell types including B cell, T cell, NCC and monocytes/macrophages (Mo/MΦ). In the meantime, the regulatory network of NCC population was predicted by WGCNA and four hub genes (Stbd1, VWF, PGP, and GRN) and one transcription factor (Hvcn1) were identified. To further study the differentiation of NCC, four subsets including memory-like NCC, mature NCC, immature NCC, and pre-NCC were revealed in NCC population for the first time. Our data will provide new insight into the biology of NCC and enable more accurate functional and developmental analysis of NCC in immune system of lower vertebrates.