AUTHOR=Lazar Katrin , Kussmann Thorsten , Pawelec Graham , Pöschel Simone , Goelz Rangmar , Hamprecht Klaus , Wistuba-Hamprecht Kilian 

TITLE=Immunomonitoring of Human Breast Milk Cells During HCMV-Reactivation

JOURNAL=Frontiers in Immunology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.723010

DOI=10.3389/fimmu.2021.723010

ISSN=1664-3224

ABSTRACT=Background: Breast milk leukocytes may play a role in protecting the infant from microbes. The dynamics and the role of lymphocytes in human cytomegalovirus (HCMV)-seropositive mothers shedding HCMV during the first months postpartum (p.p.) into breast milk are mostly unclear. 
Methods: Breast milk cells were analyzed by Pappenheim panoptic and alpha-naphthyl acetate esterase staining as well as by imaging and polychromatic flow cytometry to simultaneously establish their morphological and phenotypic properties. The latter were characterized in HCMV-seropositive and seronegative mothers´ breast milk cells at different time points p.p. 
Results: Panoptic staining of breast milk cells revealed the presence of monocytes/macrophages, granulocytes and lymphocytes. Imaging flow cytometry data combined phenotypic and morphological analysis and identified NKT-like cells, NK cells, epithelial cells, T cells and monocytes/macrophages. HCMV-seropositive but not -seronegative mothers had significantly higher T cell frequencies in mature milk. 
Conclusions: The presence of leukocyte subsets in breast milk may be more influenced by the HCMV-seropositivity of the mother than previously recognized.