Expanding Clinical Phenotype and Novel Insights into the Pathogenesis of ICOS Deficiency.

BACKGROUND: Inducible T cell co-stimulator (ICOS) deficiency has been categorized as a combined immunodeficiency often complicated by enteropathies, autoimmunity, lymphoproliferation, and malignancy. We report seven new patients and four novel ICOS mutations resulting in a common variable immunodeficiency (CVID)-like phenotype and show that dysregulated IL-12 release, reduced cytotoxic T lymphocyte-associated protein 4 (CTLA4) expression, and skewing towards a Th1-dominant phenotype are all associated with inflammatory complications in this condition. METHODS: A combination of whole exome and Sanger sequencing was used to identify novel mutations. Standard clinical and immunological evaluation was performed. FACS and ELISA-based assays were used to study cytokine responses and ICOS/ICOSL/CTLA4 expression following stimulation of whole blood and PBMCs with multiple TLR ligands, anti-CD3, and PHA. RESULTS: Four novel ICOS mutations included homozygous c.323_332del, homozygous c.451C>G, and compound heterozygous c.58+1G>A/c.356T>C. The predominant clinical phenotype was that of antibody deficiency associated with inflammatory complications in 4/7 patients. Six out of seven patients were treated with immunoglobulin replacement and one patient died from salmonella sepsis. All patients who were tested showed reduced IL-10 and IL-17 cytokine responses, normal IL-1ß, IL6, and TNF release following LPS stimulation and highly elevated IL-12 production in response to combined LPS/IFNγ stimulation. This was associated with skewing of CD4+ T cells towards Th1 phenotype and increased expression of ICOSL on monocytes. Lastly, reduced CTLA4 expression was found in 2 patients. One patient treated with ustekinumab for pancytopenia due to granulomatous bone marrow infiltration failed to respond to this targeted therapy. CONCLUSIONS: ICOS deficiency is associated with defective T cell activation, with simultaneously enhanced stimulation of monocytes. The latter is likely to result from a lack of ICOS/ICOSL interaction which might be necessary to provide negative feedback which limits monocytes activation.

Investigation of ITGB2 gene in 12 new cases of leukocyte adhesion deficiency-type I revealed four novel mutations from Iran.

BACKGROUND: Leukocyte adhesion deficiency type I (LAD-I) is a rare, autosomal recessive inherited immunodeficiency disease. LAD-I is caused by mutations in the ITGB2 gene and characterized by recurrent severe bacterial infections, as well as impaired wound healing with lack of pus formation. METHODS: In this study, we investigated ITGB2 gene mutations in 12 patients and their parents. Genomic DNA was extracted from whole blood samples. All coding regions of the ITGB2 gene were amplified using PCR and followed by direct sequencing. RESULTS: Genetic analysis revealed 12 different homozygous mutations, including six missense (c.382G>A, c.2146G>C, c.715G>A, c.691G>C, c.1777C and new c.1686C>A), two new nonsense (c.1336G>T and c.1821C>A), three-frame shift (c.1143delc, c.1907delA and new c.474dupC) and a splice site (c.1877+2T>C). Flow cytometry analysis of CD11/CD18 expression on neutrophils revealed defect in CD18 in all twelve cases (1.4% to 42%), CD11a in ten cases (0.1% to 26.7%), CD11b in nine cases (1.2% to 58.8%), and CD11c in all cases (0 % to 18.1%). The patients' parents were both heterozygous carriers. CONCLUSION: Our findings showed four new mutations in the ITGB2 gene. These results can be used for decisive genetic diagnosis, genetic counseling, as well as  prenatal diagnosis for all patients who are suspended to LADI.

Neutropenia in patients with primary antibody deficiency disorders.

Neutropenia is characterized by decrease in the absolute number of circulating neutrophils and an increase susceptibility to infections. The current study was performed in order to explain the clinical and laboratory findings of patients with antibody deficiency disorders associated neutropenia. The patients' records of 19 neutropenic cases out of 207 patients with antibody deficiencies, who had been referred to Children's Medical Center and enrolled in Iranian primary immunodeficiency registry, were reviewed. Nineteen cases (14 male and 5 female), with a mean age of 10.7+/-5.7 years, were associated with neutropenia (9.2%). The disorders with associated neutropenia were Hyper IgM syndromes (3 of 8), Common variable immunodeficiency (13 of 109), and X-linked agammaglobulinemia (3 of 45). The median age for the onset of disease and diagnosis age were 15 months (1-134) and 3.8 years (6 months-13 years), respectively. The most common infections during the course of illness were pneumonia (13 cases), diarrhea (12 cases), oral candidiasis (9 cases), otitis media (6 cases), sinusitis (6 cases), cutaneous infections (5 cases), and abscess (5 cases). Other less frequent infections were: conjunctivitis, oral ulcers, meningitis, and osteomyelitis. Three neutropenic patients died because of recurrent infections. Neutropenia may occur in any of the primary immunodeficiency disorders. Persistent or severe infections always pose a supposition, which deserves further evaluation for detecting an underlying immune deficiency syndrome and neutropenia, since a delay in diagnosis may result in a serious organ damage or even death of the patient.