FOXN1 mutation abrogates prenatal T-cell development in humans.
BACKGROUND: The transcription factor FOXN1 is implicated in the differentiation of thymic and skin epithelial cells, and alterations in it are responsible for the Nude/SCID phenotype. During a genetic counselling programme offered to couples at risk in a community where a high frequency of mutated FOXN1 had been documented, the identification of a human FOXN1(-/-) fetus gave the unique opportunity to study T cell development in utero. RESULTS: Total blockage of CD4(+) T cell maturation and severe impairment of CD8(+) cells were documented. Evaluation of the variable-domain β-chain (Vβ) families' usage among T lymphocytes revealed that the generation of T cell receptor (TCR) diversity occurred to some extent in the FOXN1(-/-) fetus, although it was impaired compared with the control. A few non-functional CD8(+) cells, mostly bearing TCRγδ in the absence of CD3, were found. DISCUSSION: FOXN1 is crucial for in utero T cell development in humans. The identification of a limited number of CD8(+) cells suggests an extrathymic origin for these cells, implying FOXN1-independent lymphopoiesis.
Vigliano, I; Gorrese, M; Fusco, A; Vitiello, L; Amorosi, S; Panico, L; Ursini, MV; Calcagno, G; Racioppi, L; Del Vecchio, L; Pignata, C
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