Natural killer cells (NK-cells), are a type of cytotoxic lymphocyte critical to the innate immune system. NK-cells respond to virus-infected cells, and also to tumor formation, and the ability to recognize stressed cells in the absence of antibodies and MHC allows for a much faster immune reaction as well as destruction of cells that cannot be detected and destroyed by other immune cells. In addition, NK-cells secret cytokines that boost the antitumor immunity and they also display memory cell-like features.
In the Blood Atlas we have 97 cell lineage enriched genes and 16 of these genes has the highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed. In addition, 378 genes are cell lineage group enriched and an additional 6 genes are enhanced in this cell lineage. Altogether, 481 genes are elevated and among these 120 also show highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed.
The NK-cells were isolated from PBMCs. Debris and cell aggregates were eliminated based on scatter profiles. Monocytes, T- and B-cells were eliminated by selecting CD14neg/SSClow and CD3neg/CD19neg sub-population of lymphocytes (FSClow/SSClow). At the final step, population of CD56+/SSClow was selected and 2,300 – 5,000 cells were sorted per sample for transcriptomic analysis by mRNA-sequencing. The transcriptome analysis shows that 53% (n=10485) of all human proteins (n=19,670) are expressed in the NK-cells and 183 of these genes show an elevated expression in NK-cells compared to the other 17 cell types (see figure below).
Figure 1. The distribution of all genes across the five specificity categories based on transcript abundance in NK-cells as well as in the other 17 cell types.
Table 1. Number of genes in the subdivided categories of elevated expression in NK-cells.
Table 2. The genes with the highest level of enriched expression in NK-cells. "pTPM" shows the transcript level as protein-coding transcripts per million. Specificity-score corresponds to the score calculated as the fold change of NK-cell expression to the second highest cell type.