TABLE 1.

ALIGNMENTS BETWEEN EARLY T CELL PRECURSOR NOMENCLATURES

Stage	Mouse postnatal	Casero, Ha	Lavaert	Le	Zeng	Kernfeld
Stage 0	(TSP ≈ Flt3⁺ ETP)	Thy1	TSP1 and TSP2	Cluster 1	Embryonic ETP	Tconv1
Stage 1	Flt3⁻ ETP	Thy1-Thy2	ETP	Cluster 2; Thy2a, 2b	Fetal ETP1?; TSP-like ETP	Tconv1
Stage 2	DN2a	Thy2	Specified	Cluster2–3; Thy2a, 2b	Fetal ETP1; proliferating ETP	Tconv1; Tconv2
COMMITMENT
Stage 3	DN2b	Thy3	Committed	Thy3; Cluster3–4	Fetal ETP2, γδ T cell precursor	Tconv2; Tconv3
Stage 4	DN3a	Thy4	Rearranging	Clusters 5–11	αβ T cell precursor2	Tconv3
References	[27, 28, 35, 37, 70, 96]	[30, 97]	[45]	[44]	[42]	[41]

Approximate correspondences based on consensus of measured developmental potentials and single-cell transcriptome similarities in postnatal T-cell precursors.

Key cell-surface marker landmarks: mouse precursors starting Kit^high, Flt3⁺, CD44^high, CD25⁻, Thy1⁻, IL7R⁻, CD4⁻ CD8⁻ TCR⁻; human precursors starting CD34⁺, (Flt3, Kit?), CD7⁻, CD1a⁻, CD44⁺, CD4⁻ CD8⁻ TCR⁻. Note that the surface marker distinguishing one “stage” from the next may not be precisely representative of the timing of the main transcriptome cluster shift

Mouse, transition stage 0 to 1: Flt3 downregulation, reduced access to DC fates.

Human, transition stage 0 to 1: onset of CD7 expression. Note that this definition only characterizes a state transition where the starting point is a classic TSP1 (CD34⁺ CD7⁻). CD7⁺ CD34-low TSP2 cells [45], likely to represent a separate precursor stream, could appear as an IRF8⁺ CD123⁺ minor subset within the Thy2⁺ population [44].

Mouse, transition stage 1–2: onset of CD25, Thy1, IL7R expression (CD7 is turned on within ETP compartment in mice, then off). More pronounced transcriptome change than in human.

Human, transition stage 1–2: increased expression of T-cell signaling genes, e.g.

Mouse, commitment: onset of Bcl11b expression (fluorescent reporter), Kit starts to go down

Human, commitment: onset of CD1a expression (no Cd1a exists in mice), CD7 and CD44 go down

Mouse, advent of rearrangement: CD44 and Kit off, RAG1 and RAG2 on

Human, advent of rearrangement: CD34 downregulated, RAG1 and RAG2 on