Maternal T Cells Protect Infants From Infectious Diseases

Technology Overview

Dr. Whitney Harrington

During pregnancy, cells transfer between the mother and fetus, and some maternal cells persist in the infant’s body after birth. This transfer of long-lived maternal cells to the offspring gives most individuals a small population of genetically distinct, maternally derived cells — a phenomenon called maternal microchimerism. The majority of these transferred cells are long-lived T cells.

Pediatrician and immunologist Whitney Harrington, MD, PhD, studies how maternal microchimerism affects early immune development, both in utero and during childhood. The goal of Dr. Harrington’s research is to develop clinical interventions to optimize the protection of offspring that is afforded by these maternal cells, for example through T cell-targeting vaccines in pregnancy.

The Harrington team is determining the factors that promote or hinder maternal microchimeric T-cell transfer, the range of antigens recognized by transferred T cells, and the effects of maternal cell interactions with the infant’s developing immune system. A key discovery by Dr. Harrington’s team is that maternal infection during pregnancy modulates microchimerism transferred to the fetus and that this can affect the infant’s susceptibility to disease.

The Harrington Lab found that maternal infection with the Plasmodium falciparum malaria parasite during pregnancy increased the number of maternal cells transferred in utero to the fetus. Subsequently, infants with maternal cells were less likely to be symptomatic when infected with malaria parasites. In the same cohort, maternal microchimerism was also associated with protecting infants from nonmalarial fever and respiratory tract infections, suggesting a more general effect on offspring immunity.

Dr. Harrington’s team also recently identified that maternal HIV infection and use of antiretroviral therapy affect microchimerism. They demonstrated that maternal HIV status influences the types of maternal T cells that offspring receive and that maternal microchimeric cells are associated with improved infant immune response to the bacille Calmette-Guérin (BCG) vaccine against tuberculosis (TB).

Methods to Study Rare Maternal Microchimeric Cells

The Harrington Lab optimized a novel process for isolating maternal cells that cross the placenta and can be extracted from cord blood. They have expertise in characterizing these cells at the single-cell level, including identifying gene expression signatures that differentiate maternal cells from infant cells. In addition, the researchers have expertise in expanding microchimeric T cells and identifying their antigen specificity. The Harrington team is now determining the mechanisms by which microchimeric cells protect infants from infections, including whether the maternal cells respond directly to pathogens or act indirectly by instructing or guiding the infant immune response.

This work is the basis for clinical applications such as optimized maternal vaccination to induce increased maternal T-cell responses to strengthen the immune protection of the offspring. For example, current recommendations for maternal vaccination during pregnancy focus on protecting infants through short-lived antibodies. In contrast, the T cells that Dr. Harrington studies have the potential to provide much longer childhood immunity against a range of infectious diseases but will likely require efficient development of specific vaccine platforms. Work from the Harrington Lab could influence maternal vaccine types and vaccination timing during pregnancy and postpartum.

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 translate her works 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

Learn More

• Whitney Harrington, MD, PhD
• Harrington Lab
• Seattle Children’s Featured Research

Publications

1. 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.
2. Mulugeta N, Peters MQ, Tobey C … Harrington WE. Peripheral regulatory T cells display dynamic memory subset frequency and inhibitory marker expression across pregnancy. Am J Reprod Immunol. 2026;95(4):e70238.
3. 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.
4. 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.
5. 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).
6. Harrington WE, Kanaan SB, Muehlenbachs A, et al. Maternal microchimerism predicts increased infection but decreased disease due to Plasmodium falciparum during early childhood. J Infect Dis 2017;215(9):1445-1451.

Last updated August 2026