Frequencies of activated T cell populations increase in breast milk of HCMV-seropositive mothers during local HCMV reactivation

Katrin Lazar; Graham Pawelec; Rangmar Goelz; Klaus Hamprecht; Kilian Wistuba-Hamprecht

doi:10.3389/fimmu.2023.1258844

Frequencies of activated T cell populations increase in breast milk of HCMV-seropositive mothers during local HCMV reactivation

Front Immunol. 2024 Jan 3:14:1258844. doi: 10.3389/fimmu.2023.1258844. eCollection 2023.

Authors

Katrin Lazar¹, Graham Pawelec^{2

3}, Rangmar Goelz⁴, Klaus Hamprecht¹, Kilian Wistuba-Hamprecht^{2

5

6}

Affiliations

¹ Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany.
² Department of Immunology, Interfaculty Institute for Cell Biology, University of Tübingen, Tübingen, Germany.
³ Cancer Solutions Program, Health Sciences North Research Institute, Sudbury, ON, Canada.
⁴ Department of Neonatology, University Children's Hospital Tübingen, Tübingen, Germany.
⁵ Section for Clinical Bioinformatics, Internal Medicine I, University Medical Center, Tübingen, Germany.
⁶ M3 Research Center, University Medical Center, Tübingen, Germany.

Abstract

Background: Human cytomegalovirus (HCMV) can reactivate in the mammary gland during lactation and is shed into breast milk of nearly every HCMV-IgG-seropositive mother of a preterm infant. Dynamics of breast milk leukocytes during lactation, as well as blood leukocytes and the comparison between both in the context of HCMV reactivation is not well understood.

Methods: Here, we present the BlooMil study that aimed at comparing changes of immune cells in blood and breast milk from HCMV-seropositive- vs -seronegative mothers, collected at four time ranges up to two months post-partum. Viral load was monitored by qPCR and nested PCR. Multiparameter flow cytometry was used to identify leukocyte subsets.

Results: CD3⁺ T cell frequencies were found to increase rapidly in HCMV-seropositive mothers' milk, while they remained unchanged in matched blood samples, and in both blood and breast milk of HCMV-seronegatives. The activation marker HLA-DR was more strongly expressed on CD4⁺ and CD8⁺ T cells in all breast milk samples than matched blood samples, but HCMV-seropositive mothers displayed a significant increase of HLA-DR⁺ CD4⁺ and HLA-DR⁺ CD8⁺ T cells during lactation. The CD4⁺/CD8⁺ T cell ratio was lower in breast milk of HCMV-seropositive mothers than in the blood. HCMV-specific CD8⁺ T cell frequencies (recognizing pp65 or IE1) were elevated in breast milk relative to blood, which might be due to clonal expansion of these cells during local HCMV reactivation. Breast milk contained very low frequencies of naïve T cells with no significant differences depending on serostatus.

Conclusion: Taken together, we conclude that the distribution of breast milk leukocyte populations is different from blood leukocytes and may contribute to the decrease of breast milk viral load in the late phase of HCMV reactivation in the mammary gland.

Keywords: CD4+ T cells; CD8+ T cells; HCMV-specific T cells; breast feeding; effector memory T cells; monocytes; viral load; virus transmission.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

CD8-Positive T-Lymphocytes
Cytomegalovirus Infections*
Cytomegalovirus*
Female
HLA-DR Antigens
Humans
Infant, Newborn
Infant, Premature
Milk, Human

Substances

HLA-DR Antigens

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The study was financed by “Sonderlinie Medizin: Verbundprojekt Freiburg-Tuebingen-Ulm” by the Ministry of Science and Arts of Baden Wuerttemberg, grant number [KL 25280-0].