Determining reference ranges for lymphocyte proliferation responses to phytohemagglutinin and Bacillus Calmette-Guérin in Iranian children.

PURPOSE: To establish reference ranges (RRs) for stimulation index of T cell proliferation triggered by phytohemagglutinin (PHA-SI) and Bacillus Calmette-Guérin (BCG-SI). METHODS: This study investigated data from 359 healthy children and 35 patients with cellular immunodeficiency as positive controls (2010-2021). We applied a colorimetric-based method (BrdU) to measure proliferation and determine the RRs at the 2.5th and 97.5th percentiles (95% confidence intervals). A cross-validation approach was performed. RESULTS: In healthy controls, the RRs for PHA-SI and BCG-SI ranged between 3 and 5.2 and 2.52 to 5.2, respectively. PHA-SI and BCG-SI were in Severe Combined Immunodeficiency (SCID) patients from 1.2 to 2.5 and 0 to 2, while in Mendelian susceptibility to mycobacterial diseases (MSMD) patients, 2.53 to 4.5 and 0.74 to 2.2, respectively. The thresholds' accuracy was checked for testing reference intervals with diagnostic effects. CONCLUSION: This study establishes PHA-SI and BCG-SI reference ranges to aid in diagnosing and treating congenital immunodeficiency diseases.

Molecular, Immunological, and Clinical Features of 16 Iranian Patients with Mendelian Susceptibility to Mycobacterial Disease.

PURPOSE: Mendelian susceptibility to mycobacterial disease (MSMD) is a rare primary immunodeficiency, triggered by non-tuberculous mycobacteria or Bacillus Calmette-Guérin (BCG) vaccines and characterized by severe diseases. All known genetic etiologies are inborn errors of IFN-γ-mediated immunity. Here, we report the molecular, cellular, and clinical features of patients from 15 Iranian families with disseminated disease without vaccination (2 patients) or following live BCG vaccination (14 patients). METHODS: We used whole blood samples from 16 patients and 12 age-matched healthy controls. To measure IL-12 and IFN-γ, samples were activated by BCG plus recombinant human IFN-γ or recombinant human IL-12. Immunological assessments and genetic analysis were also done for the patients. RESULTS: Eight patients affected as a result of parental first-cousin marriages. Seven patients originated from multiplex kindred with positive history of death because of tuberculosis or finding the MSMD-related gene mutations. Two patients died due to mycobacterial disease at the ages of 8 months and 3.7 years. The remaining patients were alive at the last follow-up and were aged between 2 and 13 years. Patients suffered from infections including chronic mucocutaneous candidiasis (n = 10), salmonellosis (n = 2), and Leishmania (responsible for visceral form) (n = 2). Thirteen patients presented with autosomal recessive (AR) IL-12Rß1 deficiency, meaning their cells produced low levels of IFN-γ. Bi-allelic IL12RB1 mutations were detected in nine of patients. Three patients with AR IL-12p40 deficiency (bi-allelic IL12B mutations) produced low levels of both IL-12 and IFN-γ. Overall, we found five mutations in the IL12RB1 gene and three mutations in the IL12B gene. Except one mutation in exon 5 (c.510C>A) of IL12B, all others were previously reported to be loss-of-function mutations. CONCLUSIONS: We found low levels of IFN-γ production and failure to respond to IL12 in 13 Iranian MSMD patients. Due to complicated clinical manifestations in affected children, early cellular and molecular diagnostics is crucial in susceptible patients.

Mendelian Susceptibility to Mycobacterial Disease due to IL-12Rß1 Deficiency in Three Iranian Children.

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare inheritance syndrome, characterized by a disseminated infection with mycobacterium in children following BCG vaccination at birth. Regarding the vaccination program in Iran, it may consider as a public health problem. The pathogenesis of MSMD is dependent on either insufficient production of IFN-gamma (γ) or inadequate response to it. Here, we want to introduce three cases including two siblings and one girl from two unrelated families with severe mycobacterial infections referred to Immunology, Asthma and Allergy Research Institute (IAARI), from 2013 to 2015; their MSMD was confirmed by both cytokine assessment and genetic analysis. Regarding the clinical features of the patients, cell proliferation against a mitogen and BCG antigen was ordered in a lymphocyte transformation test (LTT) setting. ELISA was performed for the measurement of IL-12p70 and IFN-γ in whole blood samples activated by BCG + recombinant human IFN-γ and BCG + recombinant human IL-12, respectively. In contrast to mitogen, the antigen-dependent proliferation activity of the patients' leukocytes was significantly lower than that in normal range. We identified a homozygous mutation in IL12RB1 gene for two kindred who had a homozygous mutation affecting an essential splice site. For the third patient, a novel frameshift deletion in IL12RB1 gene was found. The genetic study results confirmed the impaired function of stimulated lymphocytes to release IFN-γ following stimulation with BCG+IL-12 while the response to rhIFN-γ for IL-12p70 production was relatively intact. Our findings show that cellular and molecular assessments are needed for precise identification of immunodeficiency disorders especially those without clear-cut diagnostic criteria.

Mendelian Susceptibility to Mycobacterial Disease due to IL-12Rß1 Deficiency in Three Iranian Children.

Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare inheritance syndrome, characterized by a disseminated infection with mycobacterium in children following BCG vaccination at birth. Regarding the vaccination program in Iran, it may consider as a public health problem. The pathogenesis of MSMD is dependent on either insufficient production of IFN-gamma (γ) or inadequate response to it. Here, we want to introduce three cases including two siblings and one girl from two unrelated families with severe mycobacterial infections referred to Immunology, Asthma and Allergy Research Institute (IAARI), from 2013 to 2015; their MSMD was confirmed by both cytokine assessment and genetic analysis. Regarding the clinical features of the patients, cell proliferation against a mitogen and BCG antigen was ordered in a lymphocyte transformation test (LTT) setting. ELISA was performed for the measurement of IL-12p70 and IFN- γ in whole blood samples activated by BCG + recombinant human IFN-γ and BCG + recombinant human IL-12, respectively. In contrast to mitogen, the antigen-dependent proliferation activity of the patients' leukocytes was significantly lower than that in normal range. We identified a homozygous mutation in IL12RB1 gene for two kindred who had a homozygous mutation affecting an essential splice site. For the third patient, a novel frameshift deletion in IL12RB1 gene was found. The genetic study results confirmed the impaired function of stimulated lymphocytes to release IFN-γ following stimulation with BCG+IL-12 while the response to rhIFN-γ for IL-12p70 production was relatively intact. Our findings show that cellular and molecular assessments are needed for precise identification of immunodeficiency disorders especially those without clear-cut diagnostic criteria.