Researchers are a step closer to understanding why some vaccines offer protection for decades while others must be boosted periodically, according to a report published on Thursday in Nature Immunology.
Blood cells called megakaryocytes, known for their production of clot-forming platelets, are also playing a role in vaccine durability, they have discovered.
The researchers studied blood samples from 244 people who had received any of seven different vaccines a few days earlier, such as for seasonal influenza, yellow fever, malaria or COVID-19. They identified a molecular signature associated with the strength of antibody responses to the vaccines months later.
The signature was mostly detected in tiny bits of megakaryocyte RNA carried inside platelets. When the platelets break off from megakaryocytes and enter the bloodstream, they often take small pieces of RNA from the megakaryocytes with them, the researchers explained.
Signs of megakaryocyte activation were associated with longer-lasting antibody production. Conversely, when the researchers blocked key megakaryocyte molecules, survival of antibody-producing cells was diminished.
"The question of why some vaccines induce durable immunity while others do not has been one of the great mysteries in vaccine science," study leader Bali Pulendran of Stanford University in California said in a statement.
Megakaryocytes appear to be providing a "nurturing, pro-survival environment in the bone marrow" for antibody-producing cells, Pulendran said.
The researchers hope to learn why some vaccines might spur higher levels of megakaryocyte activation. Those findings could aid the development of vaccines that more effectively activate megakaryocytes and lead to more durable antibody responses.
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