PMC8496341_01
Analysis in vitro of the dominant negative mutation STXBP2-R190C. (A) Schematic timeline chronology of the patient illustrating the HLH onset, the HLH relapse, as well as the treatment used in each situation. (B) Cytotoxic activity during both HLH episodes (First HLH and HLH reactivation), during acute HLH phases (lower lines), and after HLH 2004 treatment (upper lines) in both episodes. The shaded area represents the mean values +-2 SD observed in healthy children (N=40). (C) COS-7 cells were transfected with an empty vector (V1) or with HA-tagged WT or mutant STXBP2 (L243R and P477L were used as negative controls). The expression levels were determined by western blot. (D) COS-7 cells were cotransfected with plasmids as indicated in the figure. After 24 h, cell lysates were immunoprecipitated with anti-GFP antibody and assessed for the presence of STXBP2 by western blot to proof the interaction with STX11-GFP. (E) RBL-2H3 cells were stably transfected with STXBP2-WT-EGFP or STXBP2-R190C-EGFP and were stimulated with PMA (5 ug/ml) and Ionomycin (1mM) for 2 and 5 h. The data shown are the mean +- SEM of two independent experiments each performed in triplicate (***p < 0.001). (F) Percentage of unmanipulated NK cells expressing CD107a after K562 stimulation from the patient, his mother, a healthy control, and 37 pediatric healthy donors used to show the reference range we use in our daily routine. The data shown are the mean +- SEM. (ns; 0.3304).
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Then, the patient required multiple treatments including cyclosporine, vp16, corticosteroids, gammaglobulins, ribavirin, cidofovir, and finally alemtuzumab, with control of viral reactivation and secondary hemophagocytic (March 2013 receives last dose of alemtuzumab), currently out of treatment, asymptomatic, without active disease ( Figure 1A ). During the loss of chimera episode and HLH reactivation, impaired NK cytotoxicity was observed with a recovery after treatment ( Figure 1B ).