TCR expression of the patient with OS. (A) Cell surface staining of the TCRαβ on CD3⁺ T cells of the patient and a healthy control in immunofluorescence flow cytometry. The percentage of TCRαβ cells in PBMCs as well as the intensity of TCRαβ expressed is comparable between the patient's T cells and a healthy control. (B) Comparison of the TCR repertoire of our patient (in black, foreground) with a patient with OS with a RAG-deficient genotype (in dark gray, middle) and an age-matched healthy control (in light gray, background). The TCR repertoire of the patient is severely restricted and matches the pattern of a RAG-deficient patient with OS, while the repertoire of the healthy control displays a Gaussian distribution.