Question

Recent studies suggest that even healthy blood contains a microbiome, most of which exists inside the white blood cells. why are there microorganisms and/or their DNA there rather than in the red blood cells; and what might their role be?

Answer 1

• Presence of micro-organisms in healthy human blood is called as healthy human blood-microbiome (HBM). Human blood consists of plasma, red blood cells (erythrocytes), white blood cells (lymphocytes) and differentt number of platelets (thrombocytes). The main function of RBCs is to carry oxygen to different parts of the body. While, White blood cells (WBCs) lymphocytes are invloved in as a surveillance/ monitoring system that monitors the blood for invasive microbes. WBCs are involved in maintaining immunity by eliminating infectious pathogens. therefore, the microorganisms or their DNA are present in White blood cells (WBCs) rather than RBCs. Also, mature RBCs lack nucleus and DNA, so microorganisms that use machinenary of host cells to replicate their own DNA cannot occur in RBCs. Also, due to absence of DNA in RBCs, they cannot carry out protein synthesis which indicates that viruses or any other microorgansim cannot evolve and survive in mammalian red blood cells.
• Human Blood microbiome role- There are billions of the microbiome found inside human body. Different components of human blood are responsible for mainitaing an infection-free state inside the body. The microorganisms present inside the body, either invades the WBCs or gets attached on the surface of the blood cells. In response to the exposure to these microorganisms the WBCs and other immune cells (B-cells, T-cells, NK cells, dendritic cells) of blood (B-cells) produces antibodies to fight against the microorganisms. These cells produces antibodies that keep the body protected against these microorganisms. thus, despite our body consists billions of microorganisms we are not easily infected by these because our immune cells have already synthesized antibodies against them.