The blood running through our veins is made up of billions of specialized cells and is responsible for many important functions inside our body, including carrying oxygen and essential nutrients to our other cells and protecting them against viruses bacteria and even cancer cells. Now, thanks to the new technique called single-cell genomics, scientists discovered four new types of blood cells in the human immune system.

The exact functions of the newly discovered cells are a mystery, for now. However, it will help improve our understanding of immune responses both in health and disease.

Dendritic And Monocyte Subtypes

Human blood contains many types of cells, including components of our immune system. Primarily, there are three types of cells in the blood: red blood cell (RBC), white blood cell (WBC) and platelets.

In this study, researchers from Massachusetts Institute of Technology have identified new classes of types of white blood cells called dendritic cells and monocytes. The dendritic cells display molecules called antigens on their surfaces and researchers found two new dendritic cell subtypes. The monocyte cells are the largest type of white blood cell, can develop into macrophages that digest debris in our cells and researchers found also two monocyte subtype.

Artistic impression of the surface of a human dendritic cell showing sheet-like folds on its surface. Image credit: NIH/Wikimedia Commons

Beside new subtypes of dendritic and monocyte cells, scientists discovered a new dendritic cell progenitor, which role is important in substitution of damaged or dead cells.

Researchers used a technique called single-cell genomics to analyze gene expression patterns in individual human blood cells. As a typical human cell consists of about 6 billion base pairs of DNA and 600 million bases of mRNA, this technique proved as very effective and can reveal previously unrecognized and rare cell types.

The study was funded by Wellcome organization and this discovery is one of the first major findings of the organization’s Human Cell Atlas project. This is the first project of its kind and is aiming to describe every cell in the human body as a reference map to accelerate progress in biomedical science.

The next study goal is to scientists figure out what each of these new cell types does in our immune system.