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Complete STAT1 deficiency is an autosomal recessive primary immunodeficiency caused by null mutations that abolish STAT1-dependent cellular responses to both IFN-[alpha]/[beta] and IFN-[gamma]. Affected children suffer from lethal intracellular bacterial and viral diseases. Here we report a recessive form of partial STAT1 deficiency, characterized by impaired but not abolished IFN-[alpha]/[beta] and IFN-[gamma] signaling. Two affected siblings suffered from severe but curable intracellular bacterial and viral diseases. Both were homozygous for a missense STAT1 mutation: g.C2086T (P696S). This STAT1 allele impaired the splicing of STAT1 mRNA, probably by disrupting an exonic splice enhancer. The misspliced forms were not translated into a mature protein. The allele was hypofunctional, because residual full-length mRNA production resulted in low but detectable levels of normally functional STAT1 proteins. The P696S amino acid substitution was not detrimental. The patients' cells, therefore, displayed impaired but not abolished responses to both IFN-[alpha] and IFN-[gamma]. We also show that recessive STAT1 deficiencies impaired the IL-27 and IFN-[gamma]1 signaling pathways, possibly contributing to the predisposition to bacterial and viral infections, respectively. Partial recessive STAT1 deficiency is what we believe to be a novel primary immunodeficiency, resulting in impairment of the response to at least 4 cytokines (IFN-[alpha]/[beta], IFN-[gamma], IFN-[gamma]1, and IL-27). It should be considered in patients with unexplained, severe, but curable intracellular bacterial and viral infections., Introduction STAT1 is a key signaling component of IFN responses. There are 2 STAT1 mRNAs, STAT1[alpha] and STAT1B, which use distinct polyadenylation sites. STAT1[alpha] is transcribed and spliced from 25 [...]

Disseminated BCG infection is a rare complication of vaccination that occurs in patients with impaired immunity. In recent years, a series of inherited disorders of the IL-12-IFN-gamma axis have been described that predispose affected individuals to disseminated disease caused by BCG, environmental Mycobacteria, and non-typhoidal Salmonella. The routine immunological work-up of these patients is normal and the diagnosis requires specific investigation of the IL-12-IFN-gamma circuit. We report here the first two such patients originating from and living in Iran. The first child is two years old and suffers from complete IFN-gamma receptor 2 deficiency and disseminated BCG infection. He is currently in clinical remission thanks to prolonged multiple antibiotic therapy. The other, a 28-year-old adult, suffers from IL-12p40 deficiency and presented with disseminated BCG infection followed by recurrent episodes of systemic salmonellosis. He is now doing well. A third patient of Iranian descent, living in North America, was reported elsewhere to suffer from IL-12Rbeta1 deficiency. These three patients thus indicate that various inherited defects of the IL-12-IFN-gamma circuit can be found in Iranian people. In conclusion we recommend to consider the disorders of the IL-12-IFN-gamma circuit in all patients with severe BCG infection, disseminated environmental mycobacterial disease, or systemic non-typhoidal salmonellosis, regardless of their ethnic origin and country of residence. [ABSTRACT FROM AUTHOR]

Background. Paracoccidioides brasiliensis is a facultative intracellular dimorphic fungus that causes paracoccidioidomycosis (P CM), the most important deep mycosis in Latin America. Only a small percentage of individuals infected by P. brasiliensis develop clinical PCM, possibly in part because of genetically determined interindividual variability of host immunity. However, no primary immunodeficiency has ever been associated with PCM. Methods. We describe the first patient, to our knowledge, with PCM and a well-defined primary immunodeficiency in the β1 subunit of the interleukin (IL)-12/IL-23 receptor, a disorder previously shown to be specifically associated with impaired interferon (IFN)-γ production, mycobacteriosis, and salmonellosis. Results. Our patient had a childhood history of bacille Calmette-Guérin disease and nontyphoid salmonellosis and, at the age of 20 years, presented to our clinic with a disseminated (acute) form of PCM. He responded well to antifungal treatment and is now doing well at 24 years of age. Conclusions. This unique observation supports previous studies of PCM suggesting that IL-12, IL-23, and IFN-γ play an important role in protective immunity to P. brasiliensis. Tuberculosis and PCM are thus not only related clinically and pathologically, but also by their immunological pathogenesis. Our study further expands the spectrum of clinical manifestations of inherited defects of the IL-12/IL-23-IFN-γ axis. Patients with unexplained deep fungal infections, such as PCM, should be tested for defects in the IL-12/IL-23-IFN-γ axis. [ABSTRACT FROM AUTHOR]

An 11-year-old girl who presented with disseminated tuberculosis associated with secondary hemophagocytosis received a diagnosis of interleukin-12 receptor β1 chain deficiency. This diagnosis of immuno deficiency should, therefore, be considered for children with disseminated tuberculosis, even in the absence of any personal or familial history of prior infection by weakly pathogenic Salmonella and Mycobacterium species. [ABSTRACT FROM AUTHOR]

Disseminated squamous cell carcinoma (SCC) of the skin is exceedingly rare in children. SCC occurs after immunodeficiency from immunosuppression in organ transplant recipients or patients with HIV infection or leukaemia, but has not been reported in primary immunodeficiencies other than epidermodysplasia verruciformis. Interferon γ receptor 2 (IFNγR2) deficiency is an exceedingly rare primary immunodeficiency, conferring almost selective predisposition to mycobacterial diseases. A disseminated, cutaneous SCC is described that occurred in a patient homozygous for a novel frameshift deletion at positions 949 and 950 (949delTG) in the IFNGR2 gene. The patient first presented at 1 year of age with disseminated Mycobacterium avium infection, with later infections of atypical mycobacteria (Mycobacterium fortuitum and Mycobacterium porcium). At 17 years of age, the patient developed multifocal SCC lesions on the face and both hands. Histopathological examination revealed well differentiated SCC. Despite local tumour excision, multiple lesions occurred and a large SCC on the right arm required amputation. The patient died at 20 years of age of disseminated SCC. Inherited disorders of IFNγ mediated immunity may predispose patients to SCC. [ABSTRACT FROM AUTHOR]

Disseminated squamous cell carcinoma (SCC) of the skin is exceedingly rare in children. SCC occurs after immunodeficiency from immunosuppression in organ transplant recipients or patients with HIV infection or leukaemia, but has not been reported in primary immunodeficiencies other than epidermodysplasia verruciformis. Interferon gamma receptor 2 (IFN gamma R2) deficiency is an exceedingly rare primary immunodeficiency, conferring almost selective predisposition to mycobacterial diseases. A disseminated, cutaneous SCC is described that occurred in a patient homozygous for a novel frameshift deletion at positions 949 and 950 (949delTG) in the IFNGR2 gene. The patient first presented at 1 year of age with disseminated Mycobacterium avium infection, with later infections of atypical mycobacteria (Mycobacterium fortuitum and Mycobacterium porcium). At 17 years of age, the patient developed multifocal SCC lesions on the face and both hands. Histopathological examination revealed well differentiated SCC. Despite local tumour excision, multiple lesions occurred and a large SCC on the right arm required amputation. The patient died at 20 years of age of disseminated SCC. Inherited disorders of IFN gamma mediated immunity may predispose patients to SCC.

Patients presenting with genetic deficiencies in IFNGR1, IFNGR2, IL-12B, and IL-12RB1 display increased susceptibility to mycobacterial infections. We analyzed in this group of patients the cross-talk between human CD4+ T lymphocytes and dendritic cells (DCs) that leads to maturation of DC into producers of bioactive IL-12 and to activation of T cells into IFN-gamma producers. We found that this cross-talk is defective in all patients from this group. Unraveling the mechanisms underlying this deficiency, we showed that IL-12 signaling in T cells is required to induce expression of costimulatory molecules and secretion of IL-12 by DCs and that IFNGR expression is required on both DCs and CD4+ T cells to induce IL-12 secretion by DCs. These data suggest that CD4+ T cell-mediated activation of DCs plays a critical role in the defense against mycobacterial infections in humans.

Background: Paracoccidioides brasiliensis is a facultative intracellular dimorphic fungus that causes paracoccidioidomycosis (PCM), the most important deep mycosis in Latin America. Only a small percentage of individuals infected by P. brasiliensis develop clinical PCM, possibly in part because of genetically determined interindividual variability of host immunity. However, no primary immunodeficiency has ever been associated with PCM., Methods: We describe the first patient, to our knowledge, with PCM and a well-defined primary immunodeficiency in the beta 1 subunit of the interleukin (IL)-12/IL-23 receptor, a disorder previously shown to be specifically associated with impaired interferon (IFN)-gamma production, mycobacteriosis, and salmonellosis., Results: Our patient had a childhood history of bacille Calmette-Guérin disease and nontyphoid salmonellosis and, at the age of 20 years, presented to our clinic with a disseminated (acute) form of PCM. He responded well to antifungal treatment and is now doing well at 24 years of age., Conclusions: This unique observation supports previous studies of PCM suggesting that IL-12, IL-23, and IFN-gamma play an important role in protective immunity to P. brasiliensis. Tuberculosis and PCM are thus not only related clinically and pathologically, but also by their immunological pathogenesis. Our study further expands the spectrum of clinical manifestations of inherited defects of the IL-12/IL-23-IFN-gamma axis. Patients with unexplained deep fungal infections, such as PCM, should be tested for defects in the IL-12/IL-23-IFN- gamma axis.

An 11-year-old girl who presented with disseminated tuberculosis associated with secondary hemophagocytosis received a diagnosis of interleukin-12 receptor beta 1 chain deficiency. This diagnosis of immunodeficiency should, therefore, be considered for children with disseminated tuberculosis, even in the absence of any personal or familial history of prior infection by weakly pathogenic Salmonella and Mycobacterium species.

The IL-12/IFN-gamma axis is crucial for protective immunity to Mycobacterium in humans and mice. Our goal was to analyze the relative contribution of various human blood cell subsets and molecules to the production of, or response to IL-12 and IFN-gamma. We designed an assay for the stimulation of whole blood by live M. bovis Bacillus Calmette-Guerin (BCG) alone, or BCG plus IL-12 or IFN-gamma, measuring IFN-gamma and IL-12 levels. We studied patients with a variety of specific inherited immunodeficiencies resulting in a lack of leukocytes, or T, B, and/or NK lymphocytes, or polymorphonuclear cells, or a lack of expression of key molecules such as HLA class II, CD40L, NF-kappaB essential modulator (NEMO), and IL-1 receptor-associated kinase-4 (IRAK-4). Patients with deficiencies in IL-12p40, IL-12 receptor beta1 chain (IL-12Rbeta1), IFN-gammaR1, IFN-gammaR2, and STAT-1 were used as internal controls. We showed that monocytes were probably the main producers of IL-12, and that NK and T cells produced similar amounts of IFN-gamma. NEMO and IRAK-4 were found to be important for IL-12 production and subsequent IFN-gamma production, while a lack of CD40L or HLA class II had no major impact on the IL-12/IFN-gamma axis. The stimulation of whole blood by live BCG thus triggers the IL-12/IFN-gamma axis by an IRAK-4- and NEMO-dependent, non-cognate interaction between monocytes, NK, and T lymphocytes.