Optimizing Breastmilk T-Cell Responses to Protect Infants From Infectious Disease
Using maternal vaccination as a tool to maximize the protection received by the infant from breastmilk
Technology Overview
Dr. Whitney Harrington
Microchimerism, the transfer of cells from mother to infant that starts in utero, results in genetically distinct maternal cells that individuals carry for decades. Transmitted cells include long-lived T cells. Pediatrician and immunologist Whitney Harrington, MD, PhD, studies how microchimerism affects an infant’s developing immune system and early response to infection.
Dr. Harrington is a leading international expert on the in utero transmission of maternal microchimeric cells and the effect these cells can have on infant susceptibility to infectious diseases. She is also a pioneer in the field of postpartum maternal microchimerism via breastmilk exposure. Studies in animals show that the unique infant gastrointestinal system allows the survival and integration of breastmilk-derived maternal T cells in infants; these cells traffic to organs such as the liver and lung.
In a key study, the Harrington Lab demonstrated that exclusively breastmilk-fed South African babies was associated with much higher levels of maternal microchimerism, suggesting that humans can also acquire maternal cells via breastfeeding. Subsequently, the researchers demonstrated that breastmilk T cells can be modulated with maternal infection or vaccination, for example the mRNA vaccine against the COVID-19 viral spike protein. Based on these observations, Dr. Harrington’s team is now studying whether the protection afforded by these T cells can be maximized through targeted maternal vaccine strategies, for example novel vaccine platforms or postpartum vaccination. Through this work, Dr. Harrington’s research extends the potential to protect infants from disease beyond the passive transfer of maternal antibodies, with a novel focus on the function of breastmilk T cells.
Dr. Harrington is interested in industry partnerships focused on improving the health of women and children. She seeks collaborations to advance her research on microchimerism and to translate her findings into clinical interventions to protect infants and children from infectious diseases. She further seeks industry partnerships to develop and apply novel sampling techniques to increase our knowledge of immune responses in women and children. She is also interested in international partnerships to diversify the participants in her studies to ensure broad clinical effectiveness of the products that develop from her work.
Stage of Development
- Preclinical in vitro
- Preclinical in vivo
- Epidemiological analysis
- Disease modeling and outcomes
Partnering Opportunities
- Collaborative research opportunity
- Sponsored research agreement
- Consultation agreement
- Tissue sample access
- Clinical trials
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Seattle Children’s Collaborators
Publications
- Petersen GL, Edlefsen PT, Li X … Harrington WE. Maternal microchimerism at birth associates with reduced odds of non-malarial fever and respiratory tract infections in Tanzanian children. PLOS Glob Public Health. 2026;6(5):e0006439.
- Peters MQ, Young WL, Stolarczuk JE … Harrington WE. Infant CD4 T-cell response to SARS-CoV-2 mRNA vaccination is restricted in cytokine production and modified by vaccine manufacturer. Open Forum Infect Dis. 2025;12(10):ofaf599.
- Armistead B, Peters MQ, Houck J … Harrington WE. Exposure to human immunodeficiency virus is associated with altered composition of maternal microchimeric T cells in infants. J Infect Dis. 2025;231(2):435-439.
- Armistead B, Jiang Y, Carlson M … Harrington WE. Spike-specific T cells are enriched in breastmilk following SARS-CoV-2 mRNA vaccination. Mucosal Immunol. 2023;16(1):39-49.
- Balle C, Armistead B, Kiravu A … Harrington WE. Factors influencing maternal microchimerism throughout infancy and its impact on infant T cell immunity. J Clin Invest. 2022;132(13).
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Last updated August 2026