Summary Antibody transfer via breastmilk represents an evolutionary strategy to boost immunity in early life. Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibodies have been observed in the breastmilk, the functional quality of these antibodies remains unclear. Here, we apply systems serology to characterize SARS-CoV-2-specific antibodies in maternal serum and breastmilk to compare the functional characteristics of antibodies in these fluids. Distinct SARS-CoV-2-specific antibody responses are observed in the serum and breastmilk of lactating individuals previously infected with SARS-CoV-2, with a more dominant transfer of immunoglobulin A (IgA) and IgM into breastmilk. Although IgGs are present in breastmilk, they are functionally attenuated. We observe preferential transfer of antibodies capable of eliciting neutrophil phagocytosis and neutralization compared to other functions, pointing to selective transfer of certain functional antibodies to breastmilk. These data highlight the preferential transfer of SARS-CoV-2-specific IgA and IgM to breastmilk, accompanied by select IgG subpopulations, positioned to create a non-pathologic but protective barrier against coronavirus disease 2019 (COVID-19). Graphical abstract Highlights • SARS-CoV-2 induces pathogen-specific antibodies in maternal blood and breastmilk • Breastmilk antibodies are functionally attenuated compared to serum antibodies • Neutrophil phagocytosis and neutralization are preferentially present in breastmilk • Disease severity, but not time since symptom onset, impacts transfer to breastmilk Pullen et al. characterize the functionality of SARS-CoV-2-specific antibodies in maternal blood and breastmilk after SARS-CoV-2 infection. Although infection elicits polyfunctional IgG in blood, breastmilk mostly contains neutralizing and neutrophil-activating IgA, IgM, and IgG, suggesting a selection of specific, non-inflammatory antibody subsets in the breastmilk.
【저자키워드】 COVID-19, Neutrophils, SARS-CoV-2, neutralization, Pregnancy, breastmilk, Fc-receptor, antibody transfer, 【초록키워드】 coronavirus disease, IgG, IgM, coronavirus, serology, antibody, SARS-COV-2 infection, severity, Antibody Response, neutrophil, Infection, serum, Characteristics, IgA, Impact, Neutralizing, phagocytosis, serum antibody, immunoglobulin A, Blood, Protective, symptom onset, acute respiratory syndrome, SARS-CoV-2-specific antibody, Abstract, individual, transfer, functions, selective, subpopulations, fluids, dominant, highlight, boost immunity, observé, functional, elicit, induce, subset, pathogen-specific, accompanied, infected with SARS-CoV-2, lactating, positioned, 【제목키워드】 SARS-COV-2 infection, functional,