Bacille Calmette-Guerin (BCG) complications in children with severe combined immunodeficiency (SCID).

Background: Bacille Calmette-Guerin (BCG) is included in the routine vaccination program in Gaza and the West Bank. Although safe, complications can occur and include local, extra-regional and disseminated BCG infection. Therefore it is contraindicated in immunodeficiencies. However, most infants are immunized prior to diagnosis of immunodeficiency. We report clinical and immunological characteristics of patients referred with severe combined immunodeficiency (SCID) who suffered from BCG complications. Methods: Files of patients referred for evaluation of immunodeficiency from January 2008 to February 2016 were retrieved. All patients have received BCG. Cell surface markers of peripheral blood mononuclear cells (PBMCs) were measured by immunofluorescent staining and flow cytometry. Serum concentrations of immunoglobulins were measured using nephelometry. Genetic diagnosis of SCID was made by direct Sanger sequencing of candidate genes. BCG complications were classified as: a) local; b) regional; c) distant; and d) disseminated disease. Results: Twenty-one children were diagnosed with SCID. BCG complications were diagnosed in 12 (57.1%). Eight patients developed local and regional disease (67%) and 4 (33%) had disseminated infection. Patients received at least three drugs: isoniazid, ethambutol and rifampicin. Outcome was relatively favorable with eight patients surviving (66.6%). No death related to BCG infection was observed. Disseminated disease was associated with reduced numbers of total lymphocytes, CD3 and CD8 levels (p < .05). Conclusions: Although high rates of BCG complications were observed, mortality was not increased and outcomes were good. Increased awareness in countries where BCG vaccine is not routinely administered and newborn screening programs for SCID could reduce complication rates.

Bacterial and Pneumocystis Infections in the Lungs of Gene-Knockout Rabbits with Severe Combined Immunodeficiency.

Using the CRISPR/Cas9 gene-editing technology, we recently produced a number of rabbits with mutations in immune function genes, including FOXN1, PRKDC, RAG1, RAG2, and IL2RG. Seven founder knockout rabbits (F0) and three male IL2RG null (-/y) F1 animals demonstrated severe combined immunodeficiency (SCID), characterized by absence or pronounced hypoplasia of the thymus and splenic white pulp, and absence of immature and mature T and B-lymphocytes in peripheral blood. Complete blood count analysis showed severe leukopenia and lymphocytopenia accompanied by severe neutrophilia. Without prophylactic antibiotics, the SCID rabbits universally succumbed to lung infections following weaning. Pathology examination revealed severe heterophilic bronchopneumonia caused by Bordetella bronchiseptica in several animals, but a consistent feature of lung lesions in all animals was a severe interstitial pneumonia caused by Pneumocystis oryctolagi, as confirmed by histological examination and PCR analysis of Pneumocystis genes. The results of this study suggest that these SCID rabbits could serve as a useful model for human SCID to investigate the disease pathogenesis and the development of gene and drug therapies.

Modulatory effect of voriconazole on the production of proinflammatory cytokines in experimental cryptococcosis in mice with severe combined immunodeficiency.

Cryptococcosis is a subacute or chronic disease. For many years, amphotericin B has been used in severe fungal infections. Voriconazole is a triazole with high bioavailability, a large distribution volume, and excellent penetration of the central nervous system (CNS). The objective of this study was to evaluate the production of pro-inflammatory cytokines in the lungs during an experimental infection caused by C. neoformans in murine model (SCID) that was treated with amphotericin B and voriconazole. After intravenous inoculation with 3.0×105 viable yeast cells, the animals were treated with amphotericin B and voriconazole. The daily treatments began 24hours after inoculation and lasted 15 days. We evaluated the survival curve and we measured the levels of TNF-α, IL-6 and IL-10. For all treatments, there was a significant increase in survival compared to the untreated group of animals and the group treated with voriconazole (maximum concentration). The levels of pro-inflammatory cytokines were significantly lower in the groups treated with voriconazole (maximum concentration) and amphotericin B (minimum concentration). Under the conditions studied, we can suggest by that the production of pro-inflammatory cytokines mediated by amphotericin B and voriconazole is dependent on the concentration administered.

Non-infectious lung disease in patients with adenosine deaminase deficient severe combined immunodeficiency.

Adenosine deaminase deficiency is a disorder of purine metabolism manifesting severe combined immunodeficiency (ADA-SCID) and systemic abnormalities. Increased levels of the substrate deoxyadenosine triphosphate (dATP) lead to immunodeficiency and are associated in a murine model with pulmonary insufficiency. We compared a cohort of patients with ADA-SCID and X-linked SCID and found that despite similar radiological and respiratory findings, positive microbiology is significantly less frequent in ADA-SCID patients (p < 0.0005), suggesting a metabolic pathogenesis for the lung disease. Clinicians should be aware of this possibility and correct metabolic abnormalities either through enzyme replacement or haematopoietic stem cell transplant, in addition to treating infectious complications.

Otitis media in children with congenital immunodeficiencies.

Otitis media represents one of the most common infections in childhood. Within the first 3 years of life, up to 80% of children experience at least one episode of otitis media. It is often resolved with supportive therapies and consequently not considered a worrisome problem. However, it may be an early manifestation of a severe underlying disease. Primary immunodeficiencies are rare congenital defects of the immune system that often remain unrecognized, or diagnosis can be delayed, sometimes resulting in fatal consequences for the child. Patients suffer from recurrent, prolonged, and/or unusual infections leading to local sequelae, failure to thrive, developmental delays, and systemic infections with severe courses. This review provides a brief insight into primary immunodeficiencies and an overview of leading findings that should result in further evaluation of the immune system in cases of otitis media. A stepwise diagnostic approach is proposed to facilitate early and accurate diagnosis and, consequently, effective and timely therapy to improve the patient's outcome and quality of life.

Serial passage of the etiologic agent of epizootic bovine abortion in immunodeficient mice.

Molecular studies have provided convincing evidence that a unique deltaproteobacterium is the causative agent of epizootic bovine abortion (EBA). Bovine fetuses, infected following dam exposure, are the only identified susceptible mammalian host. The inability to cultivate the bacterial agent of EBA (aoEBA) in vitro, associated with the substantial cost of bovine experimentation, drove efforts to identify an alternative laboratory animal host. Mice with severe combined immunodeficiency (SCID) were chosen as a potential host after immunocompetent mice proved resistant to infection. SCID mice inoculated with aoEBA-infected bovine fetal thymus homogenates began to show clinical signs at 2 months and became increasingly cachectic over the next 1-2 months. Following a 2nd passage (P2) through SCID mice, three susceptible pregnant heifers were inoculated with P2 murine tissue homogenates. All three fetuses presented with lesions indistinguishable from naturally occurring EBA, confirming successful passage of the bacterial pathogen in SCID mice. All murine (P1 and P2) and bovine fetal tissues contained aoEBA as determined by PCR; 16S bacterial ribosomal nucleotide sequences were identical in all murine and fetal bovine tissues examined. Bacteria in fetal bovine tissues were determined to be heavily opsonized, based upon microscopic evaluation of tissues stained with either FITC-conjugated anti-bovine IgG or biotin-conjugated anti-bovine IgG in conjunction with avidin-FITC. Unlike the near-term bovine fetus, the absence of an antibody response in infected SCID mice permits harvest of unopsonized bacteria for development of serologic assays.

Genetic causes of bronchiectasis: primary immune deficiencies and the lung.

Primary immune deficiencies (PID) comprise a heterogeneous group of genetically determined disorders that affect development and/or function of innate or adaptive immunity. Consequently, patients with PID suffer from recurrent and/or severe infections that frequently involve the lung. While the nature of the immune defect often dictates the type of pathogens that may cause lung infection, there is substantial overlap of radiological findings, so that appropriate laboratory tests are mandatory to define the nature of the immune defect and to prompt appropriate treatment. At the same time, the recent identification of a large number of PID-causing genes now allows early, even presymptomatic diagnosis, thus representing an essential tool for prevention of lung damage. This review article describes the most common forms of PID, their cellular and molecular bases, and the associated lung abnormalities, and reports on available treatment.

Comparative virulence of phase I and II Coxiella burnetii in immunodeficient mice.

Coxiella burnetii has two phase variants: highly virulent phase I and avirulent phase II. To examine the differences between the two phase variants in interaction with host response to infection, we performed experimental infection in immunodeficient mice. Experimental C. burnetii phase I infection in SCID mice suggested that innate immunity cannot control replication of the bacteria and that acquired immunity is essential for mice to survive infection. In this study, we used SCID and SCIDbg mice to determine whether phase II bacterial infection can be controlled in vivo.

Borrelia burgdorferi population dynamics and prototype gene expression during infection of immunocompetent and immunodeficient mice.

The population dynamics of Borrelia burgdorferi were quantified by real-time PCR targeting the flaB gene in skin (inoculation site, noninoculation site, and ear), heart (heart base and ventricle), quadriceps muscle, and the tibiotarsal joint at 1, 2, 4, 6, and 8 weeks after intradermal inoculation in C3H and C3H-scid mice. In addition, RNA transcription was assessed for several prototype genes, including flaB, ospA, ospC, dbpA, arp, vlsE, fbp, oppA-2, and p37-42. Spirochete numbers were equivalent in C3H and C3H-scid mice at 1 or 2 weeks and then declined in C3H mice, but they continued to rise and then plateaued in C3H-scid mice. Gene transcription was likewise higher in C3H-scid mice than in C3H mice, particularly at 4 or more weeks of infection. Gene transcription showed variation among tissues, with the highest levels of transcription in heart and joint tissue, which are sites of inflammation.

Nitric oxide and host defense against Pneumocystis carinii infection in a mouse model.

To investigate whether successful host defense against Pneumocystis carinii is dependent on induction of inducible nitric oxide synthase (iNOS) in alveolar macrophages, immunocompetent mice, mice depleted of CD4 lymphocytes with anti-CD4 antibody, and mice with severe combined immunodeficiency (scid) were inoculated intratracheally with P. carinii. Three weeks later, immunocompetent mice had cleared the organisms completely, while CD4 cell-depleted and scid mice were severely infected (scores, 3.6 +/- 0.2 and 2.8 +/- 0.2, respectively). Inflammation scores were significantly higher in CD4 cell-depleted mice (3.4 +/- 0.2) than in scid mice (0.6 +/- 0.2). Minimal iNOS mRNA was detectable in lung tissue from immunocompetent mice; iNOS mRNA was comparable in scid mice and mice inoculated with PBS but was 6-fold higher in CD4 cell-depleted mice. Immunohistochemistry localized iNOS protein to alveolar macrophages in CD4 cell-depleted mice. Thus, iNOS is an unlikely participant in host defense against P. carinii, because enzyme expression does not correlate with either clearance or severity of infection.

Epstein-Barr-virus-associated lymphoproliferative syndrome in severe combined immunodeficiency: establishment of a lymphoblastoid cell line as an in vitro model for biological and therapeutic studies.

Patients with primary or secondary immunodeficiency are at high risk for B cell lymphoproliferative syndromes (LPS) that are generally Epstein-Barr virus (EBV)-associated. We established a cell line, termed JuWa, from an immunoblastic lymphoma that developed in a child with severe combined immunodeficiency. JuWa cells were representative of the original lymph node as shown by a similar IgH gene rearrangement pattern. The cell line exhibited the typical features of a lymphoblastoid cell line (LCL): (1) growth pattern in large clumps, (2) lack of structural chromosome abnormalities, (3) type III latency with expression of EBV-associated EBNA2 and LMP, as well as B cell activation markers CD23 and CD30, thereby showing characteristics of an EBV producer cell line, i.e. a latent infection with a small subpopulation of cells spontaneously entering the lytic cycle, (4) inducibility of the lytic cycle by IdU and TPA, leading to an increase of early antigen and viral capsid antigen-positive cells from 1 to 15-20%, and (5) elimination of the linear viral genomes by treatment with acyclovir (ACV), without affecting the circular episomal genomes. After withdrawal of ACV, viral replication resumed within 7 days. Thus, JuWa cells support the concept of the LCL-like features of LPS and lymphomas occurring in the setting of immunodeficiency. In our in vitro model, ACV treatment could effectively suppress the viral replication but not cure EBV infection of B cells.

Macrophage-tropic HIV: critical for AIDS pathogenesis?

Human immunodeficiency virus (HIV) occurs as a number of genetic and biological variants. Of these, transmission of macrophage-tropic HIV variants appears to be favored, although most infected individuals also harbor T-cell-tropic cytopathic viruses and macrophage-tropic non-cytopathic viruses. Recent evidence regarding CD4+ T-cell depletion in vivo suggests that macrophage-tropic HIV isolates may be necessary and sufficient for the development of AIDS. This review summarizes the recent findings on macrophage-tropic viruses, and compares matched sets of experiments in HIV-infected humanized severe combined immunodeficiency (SCID) mice with a computer simulation of the lymph node microenvironment. This may help to understand why HIV infection of macrophages may have profound effects on the immune system.

Acute, lethal, natural killer cell-resistant myeloproliferative disease induced by polyomavirus in severe combined immunodeficient mice.

Infection of severe combined immunodeficient mice, which lack T and B lymphocytes, with polyomavirus (PyV) induced an acute hematological disorder leading to the death of the mice by 2 weeks postinfection. The disease was characterized by a dramatic decrease in megakaryocytes, multiple hemorrhages, anemia, thrombocytopenia, splenomegaly, a massive myeloproliferation and splenic erythroproliferation with a defect in maturation of the myeloid elements similar to that in acute leukemia. This pathology in severe combined immunodeficient mice is very different from that of the well-characterized tumor profiles induced by PyV in normal newborn or nude mice. Viral T and capsid (VP1) antigens and viral genome were detected in some cells in the spleen, but not in the majority of the proliferating myeloid cells. This suggests that the myeloproliferation is induced by some indirect mechanism, such as secretion of growth factors or cytokines by virus-infected cells, rather than by direct transformation by PyV. Neither the spread of PyV, its replication in different organs, nor the pathogenesis or the time of death were altered by depleting natural killer cells in vivo by anti-natural killer cell antibodies. Analysis of the spleen leukocyte population indicated that the cells expressed high levels of class I major histocompatibility complex antigens and were resistant to lysis by activated natural killer cells.

Chlamydia trachomatis pneumonia in the severe combined immunodeficiency (SCID) mouse.

We have developed a model of pneumonia caused by the mouse pneumonitis agent (MoPn, murine Chlamydia trachomatis) in the C.B-17 severe combined immunodeficiency (SCID) mouse. In contrast to our prior models in the nude athymic (nu/nu) and heterozygous (nu/+) mouse, SCID mice lack B-cell function and gamma delta T-cell function. SCID mice were more susceptible to MoPn than nu/nu or nu/+ mice both by criteria of mortality and quantitative lung culture. SCID mice could be reconstituted with thymocytes to be more resistant to MoPn (in the absence of significant antibody production), but the protection was modest and less than that in T-cell reconstituted nu/nu mice in our previous studies. A nu/+ MoPn-specific T-cell clone with a Th1-like cytokine profile also provided modest but significant protection without significant antibody production. The SCID mouse is a useful model to study T-cell-mediated immunity to MoPn in a B cell and gamma delta T-cell-deficient environment.

Lyme borreliosis in genetically resistant and susceptible mice with severe combined immunodeficiency.

The evolution of Lyme borreliosis was examined in genetically resistant C.B-17 and susceptible C3H/He(C3H) mice homozygous for the severe combined immune deficiency (scid) gene, or their immunocompetent counterparts. The C.B-17, C.B-17-scid, C3H, and C3H-scid mice were inoculated intradermally with 10(4) Borrelia burgdorferi and examined on days 14, 21, 30, 45, and 60 after inoculation. Spirochetemia was detected through 30 days, but was cleared in all groups by 45 days. Kidney and brain were inconsistently culture positive, but spleen and ear punch samples were positive in most mice. Immunocompetent C.B-17 and C3H mice seroconverted with equivalent IgG titers to B. burgdorferi, while C.B-17-scid and C3H-scid mice did not seroconvert. Arthritis occurred in nearly all joints examined in all genotypes on day 14, was of equal severity among C.B-17, C.B-17-scid, and C3H mice, but was more severe in C3H-scid mice. By days 30 and 45, arthritis began to resolve in immunocompetent mice, with C3H mice having more severe disease than C.B-17 mice. Arthritis persisted in C.B-17-scid and C3H-scid mice. Carditis occurred to an equal degree in all groups on day 14, remained active in scid mice, but regressed in immunocompetent mice at later intervals. Many spirochetes were visualized with silver stain in inflamed synovial tissues of scid mice, and were present in other tissues in smaller numbers. These studies show that specific immunity is not involved in arthritogenesis or genetically determined susceptibility to arthritis, but is involved in arthritis and carditis regression.

Epstein-Barr virus-induced human B-cell lymphomas in SCID mice reconstituted with human peripheral blood leukocytes.

Epstein-Barr virus (EBV) infection is associated with immunoblastic B-cell lymphomas in immunosuppressed or human immunodeficiency virus-infected individuals and in SCID mice reconstituted with human peripheral blood leukocytes (hu-PBL-SCID) from EBV-seropositive donors. The risk of tumors appearing in the hu-PBL-SCID mice differs among EBV-seropositive donors. Four different outcomes have been noted: (a) no tumors appear (no incidence donors); (b) tumors appear in a fraction of hu-PBL-SCID mice with a 10-20 week latent period (low- and intermediate-incidence donors); or (c) tumors appear in all hu-PBL-SCID mice within 6-10 weeks (high-incidence donors). The latter category of rapidly appearing tumor invariably involved activation of EBV replication, whereas more slowly growing tumors rarely activated EBV. The results indicate that prospective screening of high-risk individuals in the hu-PBL-SCID model may predict the risk of EBV-associated lymphoma development.

Immunohistological detection of human parvovirus B19 in formalin-fixed, paraffin-embedded tissues.

Human parvovirus B19 is a cause of aplastic crises in patients with haemolytic anaemias, prolonged bone marrow failure in the immunosuppressed, and fetal death secondary to non-immune hydrops. The immunohistological detection of parvovirus B19 in formalin-fixed, paraffin-embedded tissues has not previously been reported, and definitive diagnosis of infection in such specimens has relied on the use of specialized DNA hybridization and amplification techniques. A new monoclonal antibody to B19 capsid proteins, R92F6, was found to be capable of labelling infected cells in paraffin-embedded tissues from all 19 cases of parvovirus-related fetal hydrops tested, and in bone marrow from a child with congenital immunodeficiency and chronic parvovirus infection. Viral antigen was detected both in cytoplasmic and in nuclear distributions using the alkaline phosphatase anti-alkaline phosphatase (APAAP) technique without preceding proteolytic digestion. The viral epitope recognized appears to be highly conserved, as specimens were obtained over a 13-year period from widely spaced locations in the U.K. Antibody R92F6 should facilitate rapid diagnosis of parvovirus B19 infection in routinely processed and archival specimens.