ITK Gene Mutation: Effect on Survival of Children with Severe Hemophagocytic Lymphohistiocytosis

HLH as an additional warning sign of inborn errors of immunity beyond familial-HLH in children: a systematic review

Background

Hemophagocytic Lymphohistiocytosis (HLH) is a rare and life-threatening condition characterized by a severe impairment of the immune homeostasis. While Familial-HLH (FHL) is a known cause, the involvement of other Inborn Errors of Immunity (IEI) in pediatric-HLH remains understudied.

Objective

This systematic review aimed to assess the clinical features, triggers, laboratory data, treatment, and outcomes of pediatric HLH patients with IEI other than FHL (IEInotFHL), emphasizing the importance of accurate identification and management.

Methods

A systematic search for studies meeting inclusion criteria was conducted in PubMed, EMBASE, MEDLINE, and Cochrane Central. Quality assessment was performed through JBI criteria.

Results

A comprehensive search yielded 108 records meeting inclusion criteria, involving 178 patients. We identified 46 different IEI according to IUIS 2022 Classification. Combined immunodeficiencies, immune dysregulation disorders, and phagocyte defects were the IEI most frequently associated with HLH. In 75% of cases, HLH preceded the IEI diagnosis, often with an unrecognized history of severe infections. Triggers reflected the specific infection susceptibilities within IEI groups. Liver and central nervous system involvement were less common than in FHL cases. Treatment approaches and outcomes varied, with limited long-term follow-up data, limiting the assessment of therapeutic efficacy across IEI groups.

Conclusion

A comprehensive evaluation encompassing immunological, infectious, and genetic aspects is essential in pediatric-HLH. Relying solely on FHL or EBV susceptibility disorders tests is insufficient, as diverse other IEI can contribute to HLH. Early recognition of HLH as a potential warning sign can guide timely diagnostic investigations and facilitate tailored therapeutic interventions for improved outcomes.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=371425, PROSPERO, CRD42022371425.

Natural killer/T-cell lymphoma with intracranial infiltration and Epstein-Barr virus infection: A case report

BACKGROUND

Because of atypical clinical symptoms, lymphoma is easily confused with infectious diseases. Extranodal nasal-type natural killer/T-cell lymphoma (NKTL) is more common, and there are few cases of eyelid site onset and intracranial infiltration, which increases the difficulty of diagnosis. This disease usually has a very poor prognosis and there are few reports of recovery.

CASE SUMMARY

A 3-year-old boy was admitted to our hospital due to an initial misdiagnosis of "eyelid cellulitis" and failed antibiotic treatment. He was characterized by fever, right eyeball bulging, convulsions, and abnormal liver function. His blood Epstein-Barr virus (EBV) DNA was positive (8.798 × 10⁴ copies/mL), and remained positive for about half a year. The cranial imaging examination suggested a space-occupying lesion in the right eyelid, with the right temporal lobe and meninges involved. The boy underwent ocular mass resection. The pathological diagnosis was NKTL. He was diagnosed as having NKTL with intracranial infiltration, combined with chronic active EBV infection (CAEBV). Then he underwent systemic chemotherapy and intrathecal injection. The boy suffered from abnormal blood coagulation, oral mucositis, diarrhea, liver damage, and severe bone marrow suppression but survived. Finally, the tumor was completely relieved and his blood EBV-DNA level turned negative. The current follow-up has been more than 2 years and his condition is stable.

CONCLUSION

This case suggests that chemotherapy combined with intrathecal injection may have a good effect on intracranial infiltrating lymphoma and CAEBV, which deserves further study and discussion.

Magnesium Restores Activity to Peripheral Blood Cells in a Patient With Functionally Impaired Interleukin-2-Inducible T Cell Kinase

Interleukin-2-inducible T cell kinase (ITK) is critical for T cell signaling and cytotoxicity, and control of Epstein-Barr virus (EBV). We identified a patient with a novel homozygous missense mutation (D540N) in a highly conserved residue in the kinase domain of ITK who presented with EBV-positive lymphomatoid granulomatosis. She was treated with interferon and chemotherapy and her disease went into remission; however, she has persistent elevation of EBV DNA in the blood, low CD4 T cells, low NK cells, and nearly absent iNKT cells. Molecular modeling predicts that the mutation increases the flexibility of the ITK kinase domain impairing phosphorylation of the protein. Stimulation of her T cells resulted in reduced phosphorylation of ITK, PLCγ, and PKC. The CD8 T cells were moderately impaired for cytotoxicity and degranulation. Importantly, addition of magnesium to her CD8 T cells in vitro restored cytotoxicity and degranulation to levels similar to controls. Supplemental magnesium in patients with mutations in another protein important for T cell signaling, MAGT1, was reported to restore EBV-specific cytotoxicity. Our findings highlight the critical role of ITK for T cell activation and suggest the potential for supplemental magnesium to treat patients with ITK deficiency.