The molecular and phenotypic makeup of fetal human skin T lymphocytes

• Published in: Development (Cambridge) Vol. 149; no. 8
• Main Authors: Reitermaier, René, Ayub, Tanya, Staller, Julia, Kienzl, Philip, Fortelny, Nikolaus, Vieyra-Garcia, Pablo Augusto, Worda, Christof, Fiala, Christian, Staud, Clement, Eppel, Wolfgang, Scharrer, Anke, Krausgruber, Thomas, Elbe-Bürger, Adelheid
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 15.04.2022
• Subjects: Adult; Female; Fetus - cytology; Fetus - immunology; Flow Cytometry; Human Development; Humans; Male; Medicin och hälsovetenskap; Middle Aged; Skin - cytology; Skin - immunology; T-Lymphocytes - cytology; T-Lymphocytes - immunology; Human; Flow cytometry; TCR; Confocal microscopy; Fetal; Single-cell RNA-sequencing; Skin; T cells
• ISSN: 0950-1991; 1477-9129; 1477-9129
• DOI: 10.1242/dev.199781

The adult human skin contains a vast number of T cells that are essential for skin homeostasis and pathogen defense. T cells are first observed in the skin at the early stages of gestation; however, our understanding of their contribution to early immunity has been limited by their low abundance and lack of comprehensive methodologies for their assessment. Here, we describe a new workflow for isolating and expanding significant amounts of T cells from fetal human skin. Using multiparametric flow cytometry and in situ immunofluorescence, we found a large population with a naive phenotype and small populations with a memory and regulatory phenotype. Their molecular state was characterized using single-cell transcriptomics and TCR repertoire profiling. Importantly, culture of total fetal skin biopsies facilitated T cell expansion without a substantial impact on their phenotype, a major prerequisite for subsequent functional assays. Collectively, our experimental approaches and data advance the understanding of fetal skin immunity and potential use in future therapeutic interventions.