B-cells

B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype, that mature in the bone marrow. They express B cell receptors on their surface that allow them to bind specific antigens, and function in the humoral immunity component of the adaptive immune system by secreting antibodies. Additionally, B cells are classical antigen-presenting cells (APCs) and also secrete cytokines.

In the Blood Atlas we have 242 cell lineage enriched genes and 50 of these genes has the highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed. In addition, 464 genes are cell lineage group enriched and an additional 21 genes are enhanced in this cell lineage. Altogether, 727 genes are elevated and among these 152 also show highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed.

Figure 1. The distribution of all genes across the five specificity categories based on transcript abundance in B-cell lineage as well as in the other five cell lineages.

Table 1. Number of genes in the subdivided categories of elevated expression in the B-cell lineage.

Table 2. The genes with the highest level of enriched expression in B-cell lineage. "pTPM" shows the transcript level as protein-coding transcripts per million. Specificity-score corresponds to the score calculated as the fold change of B-cell lineage. expression to the second highest cell lineage.*

Naive B-cells

Naive B-cells reside in lymph nodes and are B-cells not yet exposed to an antigen. Upon antigen activation they will differentiate to either plasma cells or memory B-cells.

In the Blood Atlas we have 48 naive B-cell enriched genes and 4 of these genes has the highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed. In addition, 278 genes are cell type group enriched and an additional 193 genes are enhanced in this cell type. Altogether, 519 genes are elevated and among these 118 also show highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed.

The naive B-cells were isolated from PBMCs. Debris and cell aggregates were eliminated based on scatter profiles. Subsequently, monocytes, were eliminated by selecting CD14neg/SSClow sub-population of lymphocytes (FSClow/SSClow). B-cells population was selected as CD19+/CD3neg population. At the final step, population of CD19+/CD27neg naïve B-cells was sorted and 20,000 – 50,000 cells were sorted per sample for transcriptomic analysis by mRNA-sequencing. The transcriptome analysis shows that 54% (n=10695) of all human proteins (n=19,670) are expressed in the naive B-cells and 278 of these genes show an elevated expression in naive B-cells compared to the other 17 cell types (see figure below).

Figure 2. The distribution of all genes across the five specificity categories based on transcript abundance in naive B-cells-cells as well as in the other 17 cell types.

Table 3. Number of genes in the subdivided categories of elevated expression in naive B-cells.

Table 4. The genes with the highest level of enriched expression in naive B-cells. "pTPM" shows the transcript level as protein-coding transcripts per million. Specificity-score corresponds to the score calculated as the fold change of naive B-cell expression to the second highest cell type.

Memory B-cells

Memory B-cells are formed within germinal centers following primary infection, and are important in generating an accelerated and more robust antibody-mediated immune response in the case of re-infection. They are localized in areas of facilitated antigen encounter and compared to naive B-cells they have higher affinity to the immunizing antigen, a lifespan of decades instead of weeks, and faster and more efficient proliferation and differentiation.

In the Blood Atlas we have 45 memory B-cell enriched genes and 4 of these genes has the highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed. In addition, 284 genes are cell type group enriched and an additional 189 genes are enhanced in this cell type. Altogether, 518 genes are elevated and among these 121 also show highest expression in blood or lymphoid tissues when comparing all tissues and organs analysed.

The memory B-cells were isolated from PBMCs. Debris and cell aggregates were eliminated based on scatter profiles. Subsequently, monocytes were eliminated by selecting CD14neg/SSClow sub-population of lymphocytes (FSClow/SSClow). B-cells population was selected as CD19+/CD3neg population. At the final step, population of CD19+/CD27+ memory B-cells was sorted and 5,000 – 19,000 cells were sorted per sample for transcriptomic analysis by mRNA-sequencing. The transcriptome analysis shows that 53% (n=10370) of all human proteins (n=19,670) are expressed in the memory B-cells and 284 of these genes show an elevated expression in memory B-cells compared to the other 17 cell types (see figure below).

Figure 3. The distribution of all genes across the five specificity categories based on transcript abundance in memory B-cells as well as in the other 17 cell types.

Table 5. Number of genes in the subdivided categories of elevated expression in memory B-cells.

Table 6. The genes with the highest level of enriched expression in memory B-cells. "pTPM" shows the transcript level as protein-coding transcripts per million. Specificity-score corresponds to the score calculated as the fold change of memory B-cells expression to the second highest cell type.