# Milk Butryophilin and Immune Tolerence

> **NIH NIH R21** · YALE UNIVERSITY · 2024 · $251,250

## Abstract

Project Summary/Abstract
In addition to supplying nutrients to support growth, breast milk also has important immune functions that
provide protection against infection and influence the maturation of the neonatal immune system. Many
epidemiological studies have demonstrated that breastfeeding protects against a variety of allergic and
autoimmune diseases and several rodent models have demonstrated that breast milk fosters lasting immune
tolerance to specific environmental antigens. In this application, we focus on the potential immune modulating
effects of butyrophilin (BTN1A1). BTN1A1 is structurally related to the B7 co-signaling molecules that regulate
T cell activation or tolerance. It is expressed in the apical membrane of mammary epithelial cells during
lactation and participates in the trafficking and secretion of intracellular lipid droplets from mammary epithelial
cells into milk. We now present preliminary data showing that the BTN1A1 found in milk also regulates T cell
responsiveness, both within the neonatal gut as well as systemically. Furthermore, the effects of BTN1A1 on T
cell responsiveness persist well after the exposure to BTN1A1 ends at weaning. Therefore, our hypothesis is
that that BTN1A1 contributes to the development of immune tolerance in neonates and is required for breast
milk to inhibit the development of reactive airway disease to the environmental antigen, ovalbumin. The goal of
this R21 application is to test this hypothesis through two “high-risk” but “high-reward” aims. Aim 1 will begin
to characterize the molecular pathways by which milk BTN1A1 inhibits T cell activation by utilizing the power of
unbiased, high-throughput sequencing techniques. We propose: 1) single-cell RNA sequencing (scRNAseq) of
splenic T cells from mice that consumed milk±BTN1A1; 2) scRNAseq on T cells isolated from peripheral blood
mononuclear cells (PBMCs) derived from healthy human donors and exposed to anti-CD3/28 ± recombinant
BTN1A1; and 3) the assay for transposase-accessible chromatin using sequencing (ATAC-seq) to define
BTN1A1-dependent epigenetic changes in T cells. Aim 2 will test whether BTN1A1 mediates immune
tolerance to environmental allergens in vivo. Exposing lactating mothers to Ova has been shown to generate
tolerance to Ova in their suckling offspring, preventing Ova-induced reactive airway disease in those offspring
when they are challenged with Ova after weaning. Using this experimental paradigm, we will test whether
BTN1A1 is required for the protective effect of breast milk against Ova-induced lung disease. The proposed
studies investigating the immune regulating functions of BTN1A1 will contribute important knowledge regarding
how breast milk affects the neonatal immune system and lowers the risk of atopy and autoimmunity.

## Key facts

- **NIH application ID:** 10894979
- **Project number:** 1R21HD111764-01A1
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Insoo Kang
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $251,250
- **Award type:** 1
- **Project period:** 2024-05-02 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10894979

## Citation

> US National Institutes of Health, RePORTER application 10894979, Milk Butryophilin and Immune Tolerence (1R21HD111764-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10894979. Licensed CC0.

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