Infographic: How Vaccines Train Innate Immunity
Infographic: How Vaccines Train Innate Immunity

Infographic: How Vaccines Train Innate Immunity

A recent study elucidates some of the changes that occur in the body after inoculation with a tuberculosis vaccine.

Shawna Williams
Shawna Williams
Nov 1, 2020

ABOVE: © TERESE WINSLOW

While researchers have observed for decades that certain vaccines seem to help recipients ward off more than just the target pathogen, only in recent years have they identified possible mechanisms for these bonus benefits. For example, in a study published this year (depicted here), researchers examined immune cells from the blood and bone marrow of healthy adults before and after they received a live tuberculosis vaccine known as bacille Calmette-Guérin, or BCG.

© TERESE WINSLOW

In the bone marrow post-vaccination, genes are expressed that trigger hematopoietic stem and progenitor cells to differentiate into monocytes, neutrophils, and other so-called myeloid cells. In a separate analysis of the effects of BCG in newborns, the researchers found that the vaccine ramped up the number of neutrophils in babies’ blood compared with unvaccinated infants.

© TERESE WINSLOW

Monocytes from the blood displayed epigenetic changes after vaccination that opened chromatin harboring multiple genes involved in driving an inflammatory response, making them more accessible for transcription. Meanwhile, chromatin closed around genes associated with immune tolerance.

When exposed to the fungal pathogen Candida albicans in vitro, immune cells sampled from patients’ blood 90 days after vaccination released more of the cytokine interleukin 1β, which mediates inflammation, than did cells from blood drawn from the same individuals before vaccination.

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Correction (November 13): Incorrect labels of the open and closed chromatin in the graphic have been corrected. The Scientist regrets the error.