Pre-existing antibodies linked to different immune responses after influenza vaccination

Influenza vaccines are updated regularly to provide protection against circulating strains, but responses to vaccination can vary between individuals.

Previous exposure to influenza viruses and vaccines can leave behind pre-existing antibodies, which may influence how the immune system responds to later vaccination. However, how these antibodies are associated with subsequent B-cell responses remains incompletely understood.

B-cell responses to vaccination

In a study published in Virologica Sinica, a team of researchers followed 21 adults before and after seasonal influenza vaccination. Using flow cytometry, B-cell receptor sequencing, and monoclonal antibody characterization, they examined how baseline antibody levels were associated with B-cell responses after vaccination.

The study improves understanding of how pre-existing immunity relates to vaccine-induced immune responses and may provide insights for future influenza vaccine development.

“We found that individuals with different pre-vaccination antibody levels showed distinct patterns of HA-binding B-cell responses,” shares senior and co-corresponding Yong Gao. “Participants with higher baseline antibody titers showed increased frequencies of HA⁺CD27⁻IgD⁺ naive-phenotype B cells and B-cell receptor features associated with less maturation.”

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In contrast, B-cell receptors and antibodies from lower-titer groups showed greater mutation levels, broader class switching, and broader neutralizing activity against historical influenza strains.

“Our findings highlight that pre-existing antibody levels are associated with different patterns of B-cell maturation and antibody breadth following influenza vaccination,” Gao says.