By now, it is easy to believe that scientists may have already discovered everything there is to know about the human body, what with the countless studies done on it. Just when you think there's nothing more about mankind's anatomy can surprise you, a new research discovered four new types of blood cells that scientists have never known before.

Blood used to be identified by observing the proteins on their surface, which is a technique that may miss to see rare blood cell classes, IFL Science reported. To make this technique more accurate, researchers use single-cell genomics, allowing them to see the details in each gene expressed by the proteins on the surface of the blood. Through this, scientists have a clearer picture of the type of blood cell they are looking at.

Using the single cell-genomics technique, the scientists discovered four new types of blood cell classes, Wellcome reported. White blood cells have subcategories that play specific parts in protecting the body from infection, which is an important part of the immune system. Now, the new study published in "Science" uncovered two new classes of dendritic cells and two new monocyte cell types.

Dendritic cells link the innate immune system and the adaptive immune system. Innate immune system includes the skin and membranes that protects the body from infections. Meanwhile, adaptive immune system eliminates pathogens and makes sure the body remembers the same infection that attacks the body again.

Dendritic cells basically take up parts of antigen that infects the body and shows it on the surface to alarm the T-cells, which then finds and kills the pathogen. Meanwhile monocyte cells are the biggest kinds of white blood cells that are known as macrophages. The monocyte cells go to where the infection is to eat up the pathogens and remove them from the body. Wellcome's Infection and Immunobiology's Divya Shah said the study used new cutting-edge technologies that can uncover new types of cells that scientists didn't originally know.