STAT5b sequencing from sorted fractions of patients 3 and 4. (A) In patient 3 (Table 1) with STAT5b N642H mutation, leukemic LGLs expressed CD3 and CD56. (B) Leukemic CD3⁺CD56⁺ cells and (C) CD3⁺CD16/56^neg control cells were sorted with flow cytometry. (B-C) The purity of sorted fractions. By capillary sequencing, the mutation N642H is visible in (D) the MNC fraction and in (E) the CD3⁺CD16/56⁺ fraction, but not in (F) CD3⁺CD16/56^neg cells. (G) The phenotype of leukemic cells in patient number 4 (Table 1) was CD3^negCD16/56⁺ NK cell, but also CD3⁺ T cells aberrantly expressed CD56 antigen. Both (H) CD3^negCD16/56⁺ and (I) CD3⁺CD16/56⁺ cells were sorted by flow cytometry, and the panels show purity of sorted fractions. By capillary sequencing, the mutation N642H was present in (J) MNCs, but also in (K-L) both of the sorted fractions, suggesting that the aberrant CD3⁺CD56⁺ cells also belong to the leukemic clone.