Eugenio Galli1,2, Silvia Bellesi1, Marcello Viscovo2, Federica Sorà1,2, Stefan Hohaus1,2, Nicola Piccirillo1,2, Luca Laurenti1,2, Patrizia Chiusolo1,2, Valerio De Stefano1,2, Simona Sica1,2 and Gina Zini1,2.
Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed
Ematologia, Fondazione Policlinico Universitario A. Gemelli IRCCS,
2 Sezione di Ematologia, Dipartimento di Scienze Radiologiche ed Ematologiche, Universita’ Cattolica del Sacro Cuore, Rome, Italy.
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To the editor
|Figure 1. Morphology of CAR-T cells. A. Residual CAR-T cells washed out from the infusion bags of patient 1. The heterogeneous population includes lymphoid cells of variable size with often indented or lobulated immature-looking nuclei and grey to hyperbasophilic cytoplasm. Giant, immunoblast-like cells with immature chromatin are also present, sometimes with multiple molded nucleoli, and hyperbasophilic cytoplasm with granules, occasional vacuoles, and a hypertrophic Golgi clear para-nuclear area. Large granular lymphocytes, apoptotic and smudge cells were also present. B. Residual CAR-T cells washed out from the infusion bags of patient 2. Large hyperbasophilic immunoblast-like cells are visible, togheter with more mature-looking cells with hyperchromatic and multi-folded nuclei. Nuclear lobularity in these last is likely accentuated by a cytospin articfact. C. Peripheral blood smear of patient 2. Several circulating cells display similar morphological features, such as large size, basophilic cytoplasm and indented nuclei.|
|Figure 2. Flow cytometric analysis of CAR-T cells from infusion batches of patient 1. A. CD3+ CAR-T cells are well identifiable in the box in the right. B. Total CD3+ CAR events are represented in the plot and split into the two subpopulations of CD4+ CAR-T cells (lower right) and CD8+ CAR-T cells (upper left). C. SSC MFI (Median Fluorescence Intensity) value of CD4+ CAR-T cells (dark grey) compared to CD4+ non-CAR-T cells (light grey). D. FSC MFI (Median Fluorescence Intensity) value of CD4+ CAR-T cells (dark grey) compared to CD4+ non-CAR-T cells (light grey).|