Figure 2.

T-cell differentiation blocks in RAG-deficient patients and mice. Representation of T-cell development in mice and humans, with the list of surface markers that can be used to identify the different stages of maturation. Stages at which RAG genes are expressed, and the concurrent nature of VDJ recombination products detected at each stage, are indicated at the bottom. Proliferating cells are indicated by a circular arrow. The red boxes indicate the stage at which development is blocked in RAG deficiency. Of note, use of artificial thymic organoids (ATOs) allowed to establish that T-cell development in RAG-mutated patients occurs at the preselection double-positive (DP) stage, unlike what was found in mice, where the block is present at the double-negative 3 (DN3) stage. DN, double negative; DP, double positive; ETP, early thymic progenitor; GL, germline; HSC, hematopoietic stem cell.