Comparing the levels of CTLA-4-dependent biological defects in patients with LRBA deficiency and CTLA-4 insufficiency.

BACKGROUND: Lipopolysaccharide-responsive beige-like anchor protein (LRBA) deficiency and cytotoxic T-lymphocyte protein-4 (CTLA-4) insufficiency are recently described disorders that present with susceptibility to infections, autoimmunity, and lymphoproliferation. Clinical and immunological comparisons of the diseases with long-term follow-up have not been previously reported. We sought to compare the clinical and laboratory manifestations of both diseases and investigate the role of flow cytometry in predicting the genetic defect in patients with LRBA deficiency and CTLA-4 insufficiency. METHODS: Patients were evaluated clinically with laboratory assessments for lymphocyte subsets, T follicular helper cells (TFH ), LRBA expression, and expression of CD25, FOXP3, and CTLA4 in regulatory T cells (Tregs) at baseline and 16 h post-stimulation. RESULTS: LRBA-deficient patients (n = 29) showed significantly early age of symptom onset, higher rates of pneumonia, autoimmunity, chronic diarrhea, and failure to thrive compared to CTLA-4 insufficiency (n = 12). In total, 29 patients received abatacept with favorable responses and the overall survival probability was not different between transplanted versus non-transplanted patients in LRBA deficiency. Meanwhile, higher probability of survival was observed in CTLA-4-insufficient patients (p = 0.04). The T-cell subsets showed more deviation to memory cells in CTLA-4-insufficiency, accompanied by low percentages of Treg and dysregulated cTFH cells response in both diseases. Cumulative numbers of autoimmunities positively correlated with cTFH frequencies. Baseline CTLA-4 expression was significantly diminished in LRBA deficiency and CTLA-4 insufficiency, but significant induction in CTLA-4 was observed after short-term T-cell stimulation in LRBA deficiency and controls, while this elevation was less in CTLA-4 insufficiency, allowing to differentiate this disease from LRBA deficiency with high sensitivity (87.5%) and specificity (90%). CONCLUSION: This cohort provided detailed clinical and laboratory comparisons for LRBA deficiency and CTLA-4 insufficiency. The flow cytometric approach is useful in predicting the defective gene; thus, targeted sequencing can be conducted to provide rapid diagnosis and treatment for these diseases impacting the CTLA-4 pathway.

A Case of Ataxia-telangiectasia Presented With Hemophagocytic Syndrome.

Ataxia-telangiectasia (A-T) is a multisystem disease caused by a genetic defect located on the long arm of chromosome 11 (11p22-23). The gene defect results in the loss of A-T-mutated protein, subsequently leading to unrepaired DNA fractures and defects in the signal transduction pathway. As a result, characteristic findings arise, including recurrent sinopulmonary infections, hypersensitivity against ionized radiation with the tendency to develop cancer related to progressive cerebellar ataxia, pathognomonic oculocutaneous telangiectasias, varying degrees of humoral and cellular immunodeficiency, and infertility. This case report presents a 3-year-old male patient with A-T who developed hemophagocytic syndrome. To the best of our knowledge, no such case has been previously reported.

Hemophagocytic bone marrow aplasia with plasma cells in a RAG2-deficient SCID case after a nonconditioned transplantation from a fully matched sibling.

We report a RAG2-deficient patient with severe combined immunodeficiency and hemophagocytic bone marrow aplasia with plasma cells after a nonconditioned transplantation from a fully matched sibling. After engraftment, disseminated BCGosis appeared because of graft versus host disease prophylaxis. On the 55th day, eosinophilia, neutropenia, and thrombocytopenia developed. Aplasia, hemophagocytic histiocytes, and plasma cells were found on his bone marrow with very high level of serum immunoglobulin E. We could not discriminate exactly whether BCGosis or alloimmune response is the cause of hemophagocytic aplasia with plasma cells. Despite the second hematopoietic stem cell transplantation with a reduced intensity conditioning regime, his marrow aplasia did not recover and he died. This case suggests that BCGosis might be associated with hemophagocytic marrow aplasia with plasma cells in an alloimmune reaction.