Researchers reveal how immune memory cells are stored in bone marrow

Researchers reveal how immune memory cells are stored in bone marrow

The researchers revealed how vaccines work and how they produce immune cells that have a long lifespan, often for decades. These immune cells offer a protective barrier that can prevent or minimize reinfection and a memory that allows us to recognize a past invader like a virus and get rid of it before it causes disease. Although it has long been known that these “long-lived plasma cells” are important, how and when they are created after immunization is still unknown. These cells produce the antibody that acts as a barrier in our blood.

A research team led by Dr Marcus Robinson and Professor David Tarlinton from Monash University’s Immune Memory Laboratory, and published in the prestigious journal Science Immunology, has shown in real time how immune memory cells are stored in the bone marrow at around a single cell per hour for several weeks after immunization. The researchers used a genetic system in mice to map the gradual accumulation of these cells. This system, called time stamping, allows researchers to indelibly mark all the plasma cells present at a given time after vaccination and then go back and identify those that have survived and are therefore long-lived. By doing this regularly after vaccination, the researchers revealed the history of the accumulation of these long-lived cells, pinpointing when they were produced and where they went.

After receiving a vaccine, we remain largely immune to that disease because our bodies provide a continual supply of antibodies against the immunized disease, essentially making sure that we remain replete with these antibodies. While we know the sites in the body where these long-lived plasma cells were generated, including the lymph nodes, tonsils, and intestine, exactly what causes some vaccines to make these cells last for decades compared to vaccines is unknown. They disappear after a few months. . Given the worldwide interest in the long-term immunity provided by COVID vaccines, there is an increased urgency in understanding this process.

Using a mouse model that expressed a fluorescent protein (called the TdTomato protein) only in cells that produced antibodies specifically against a specific vaccine. Because these cells fluoresced, it was possible to track individual cells as they were produced and where they were stored. The research used a series of tools to identify only those plasma cells that were generated by the vaccine. All the plasma cells in the mouse model expressed a fluorescent protein (called the TdTomato protein), and among them, they identified the ones that recognized the vaccine and eventually, by using the timestamp, they knew when those cells had been produced. and therefore how old they were.

According to Professor Tarlinton, studying these individual cells as they are born, mature and stored to protect us against repeated invasion by a particular virus or bacteria “may inform our understanding of how the recruitment of long-lived plasma cells occurs”. The complexity of the study has allowed researchers to determine other aspects of the construction of specific immunity:

How do these plasma cells enter the bone marrow? Whether these plasma cells must crowd out other cells when they are stored in areas such as the bone marrow, or whether these cells “find” a niche that was left vacant because the earlier plasma cells died or moved elsewhere. Mapping of these cells revealed that a particular vaccination in one mouse led to the generation of around 40,000 persistent plasma cells in the bone marrow. These cells, after initial budding, then decline at a rate of around 0.1% per day with a half-life of approximately 700 days, providing an estimate of the duration of protection and identifying for further study own long-lived cells.

According to Professor Tarlinton, understanding how these long-lived plasma cells are generated, live and die “will inform our ability to modulate their recruitment, through different combinations of vaccines or delivery strategies, ultimately allowing us to increase the longevity of the immunity”. ” he said. “In fact, there is exciting work recently published in Nature that describes how altering the mechanics of vaccination can dramatically influence the character of the immune response, and we would predict the production of these special cells that have been the focus of our work.” (AND ME)

(This story has not been edited by Devdiscourse staff and is automatically generated from a syndicated feed.)

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