Howard M. Rosenblatt

Interleukin-2 receptor γ chain mutation results in X-linked severe combined immunodeficiency in humans

The interleukin-2 (IL-2) receptor gamma chain (IL-2R gamma) is a component of high and intermediate affinity IL-2 receptors that is required to achieve full ligand binding affinity and internalization. We have localized the IL-2R gamma gene to human chromosome Xq13. Genetic linkage analysis indicates that the IL-2R gamma gene and the locus for X-linked severe combined immunodeficiency (XSCID) appear to be at the same position. Moreover, we demonstrate that each of three unrelated patients with XSCID has a different mutation in his IL-2R gamma gene resulting in a different premature stop codon and predicted C-terminal truncation. These data establish that XSCID is associated with mutations of the IL-2R gamma gene product. Since XSCID is characterized by absent or markedly reduced numbers of T cells, our findings imply that IL-2R gamma plays a vital role in thymic maturation of T cells. These results also have important implications for prenatal and postnatal diagnosis, carrier female detection, and gene therapy for XSCID.

CD40 ligand gene defects responsible for X-linked hyper-IgM syndrome

The ligand for CD40 (CD40L) is a membrane glycoprotein on activated T cells that induces B cell proliferation and immunoglobulin secretion. Abnormalities in the CD40L gene were associated with an X-linked immunodeficiency in humans [hyper-IgM (immunoglobulin M) syndrome]. This disease is characterized by elevated concentrations of serum IgM and decreased amounts of all other isotypes. CD40L complementary DNAs from three of four patients with this syndrome contained distinct point mutations. Recombinant expression of two of the mutant CD40L complementary DNAs resulted in proteins incapable of binding to CD40 and unable to induce proliferation or IgE secretion from normal B cells. Activated T cells from the four affected patients failed to express wild-type CD40L, although their B cells responded normally to wild-type CD40L. Thus, these CD40L defects lead to a T cell abnormality that results in the failure of patient B cells to undergo immunoglobulin class switching.

Epstein–Barr Virus–Associated B-Cell Proliferations of Diverse Clonal Origins after Bone Marrow Transplantation in a 12-Year-Old Patient with Severe Combined Immunodeficiency

A 12-year-old boy with severe combined immunodeficiency who had been kept in a gnotobiotic environment since birth received bone marrow from a histoincompatible sibling in an attempt to reconstitute immunologic function. To prevent graft versus host disease, the donors marrow was treated in vitro with monoclonal antibody and complement to remove alloreactive T cells. Eighty days after transplantation, the patient had a systemic illness characterized by fever, thrombocytopenia, gastrointestinal pain, and bleeding; he died on the 124th post-transplantation day. Postmortem examination revealed multiple tumor-like B-cell proliferations, recipient in origin, in numerous organs. Epstein-Barr virus (EBV) was isolated from the patients pharyngeal secretions; EBV nuclear antigen was found in spontaneously transformed peripheral-blood lymphocytes, inflammatory cells from peritoneal fluid, and bone marrow cells; and EBV genomes were discovered in all tumor tissues. The donors serum showed evidence of past EBV infection. Analysis of cellular immunoglobulin and immunoglobulin gene DNA from the tumors indicated both monoclonal and oligoclonal B-cell proliferations. These findings provide evidence for the evolution of EBV-induced polyclonal activation of B cells to oligoclonal B-cell proliferation and finally to monoclonal B-cell lymphoma.

Vaccine-Acquired Rotavirus in Infants with Severe Combined Immunodeficiency

Live pentavalent human-bovine reassortant rotavirus vaccine is recommended in the United States for routine immunization of infants. We describe three infants, two with failure to thrive, who had dehydration and diarrhea within 1 month after their first or second rotavirus immunization and subsequently received a diagnosis of severe combined immunodeficiency. Rotavirus was detected, by means of reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay, in stool specimens obtained from all three infants, and gene-sequence analysis revealed the presence of vaccine rotavirus. These infections raise concerns regarding the safety of rotavirus vaccine in severely immunocompromised patients.

Extraintestinal rotavirus infections in children with immunodeficiency

Some rotavirus strains, including vaccine candidates, have been demonstrated to cause hepatitis in immunodeficient and malnourished mice and to grow in human liver cells. To determine whether rotavirus spreads outside the intestine in naturally infected children, we examined tissues from four immunodeficient children affected with severe combined immunodeficiency disease, acquired immunodeficiency disease syndrome, or DiGeorge syndrome. Chronic rotavirus-related diarrhea, which persisted until death, had also developed in each child. Using indirect immunoperoxidase techniques, we identified rotavirus antigen in the liver and kidney with a hyperimmune guinea pig antiserum prepared to double-shelled rotavirus particles. Similar immunostaining with an antiserum to a rotavirus nonstructural protein (NS26) provided evidence of active virus replication. The observed reactivity was eliminated specifically when serial sections were immunostained with the same antiserum that had been absorbed with either double-shelled rotavirus particles or NS26. Immunostaining was not observed in the liver of children with other diseases (alpha 1-antitrypsin deficiency, inspissated bile syndrome, and acute rejection of a transplanted liver). These findings demonstrate that rotavirus infections in children can extend beyond the intestinal tract. Further studies are warranted to determine whether extraintestinal rotavirus replication occurs in children without severe immunodeficiency, such as malnourished children.

Immunogenicity, safety, and predictors of response after a pneumococcal conjugate and pneumococcal polysaccharide vaccine series in human immunodeficiency virus-infected children receiving highly active antiretroviral therapy

Background: The immunogenicity and safety of 2 doses of pneumococcal conjugate vaccine (PCV) and 1 dose of pneumococcal polysaccharide vaccine (PPV) were evaluated in human immunodeficiency virus (HIV)-infected children receiving highly active antiretroviral therapy (HAART). Methods: Children 2 to <19 years, receiving stable HAART for ≥3–6 months, with HIV RNA PCR <30,000–60,000 copies/mL, received 2 doses of PCV and 1 dose of PPV at sequential 8-week intervals. Antibodies to pneumococcal serotypes (STs) 1 (PPV only) and 6B, 14, 19F, and 23F (PCV and PPV) were measured by ELISA. Results: Two hundred sixty-three subjects were enrolled, of whom 225 met criteria for inclusion in the primary dataset. Antibody concentrations were low at entry, despite previous PPV in 75%. After vaccination, 76%–96% had concentrations ≥0.5 &mgr;g/mL and 62–88% ≥1.0 &mgr;g/mL to the 5 STs (geometric mean concentrations [GMCs] = 1.44–4.25 &mgr;g/mL). Incremental gains in antibody concentration occurred with each vaccine dose. Predictors of response included higher antibody concentration at entry, higher immune stratum (based on nadir CD4% before HAART and CD4% at screening), lower entry viral RNA, longer duration of the entry HAART regimen, and age <7 years. Response was more consistently related to screening CD4% than nadir CD4%. Seven percent had vaccine-related grade 3 events, most of which were local reactions. Conclusions: Two PCVs and 1 PPV were immunogenic and safe in HIV-infected children 2 to <19 years who were receiving HAART. Responses were suggestive of functional immune reconstitution. Immunologic status based on nadir and, especially, current CD4% and control of HIV viremia were independent determinants of response.

The pediatric pulmonary and cardiovascular complications of vertically transmitted human immunodeficiency virus (P2C2 HIV) infection study: Design and methods

The P2C2 HIV Study is a prospective natural history study initiated by the National Heart, Lung, and Blood Institute in order to describe the types and incidence of cardiovascular and pulmonary disorders that occur in children with vertically transmitted HIV infection (i.e., transmitted from mother to child in utero or perinatally). This article describes the study design and methods. Patients were recruited from five clinical centers in the United States. The cohort is composed of 205 infants and children enrolled after 28 days of age (Group I) and 612 fetuses and infants of HIV-infected mothers, enrolled prenatally (73%) or postnatally at age < 28 days (Group II). The maternal-to-infant transmission rate in Group II was 17%. The HIV-negative infants in Group II (Group IIb) serves as a control group for the HIV-infected children (Group IIa). The cohort is followed at specified intervals for clinical examination, cardiac, pulmonary, immunologic, and infectious studies and for intercurrent illnesses. In Group IIa, the cumulative loss-to-follow-up rate at 3 years was 10.5%, and the 3-year cumulative mortality rate was 24.9%. The findings will be relevant to clinical and epidemiologic aspects of HIV infection in children.

A novel X-linked combined immunodeficiency disease.

A novel X-linked combined immunodeficiency disease was found in five living males in an extended family in the United States. The age of the affected males ranged from 2.5 to 34 yr. The most prominent clinical abnormalities were a paucity of lymphoid tissue; recurrent sinusitis, otitis media, bronchitis, and pneumonia; severe varicella; and chronic papillomavirus infections. The principal immunologic features of the disorder were normal concentrations of serum immunoglobulins but restricted formation of IgG antibodies to immunogens; normal numbers of B cells and NK cells but decreased numbers of CD4+ and CD8+ T lymphocytes, particularly the CD45RA+ subpopulations; diminished proliferative responses of blood T cells to allogeneic cells, mitogens and antigens; and decreased production of IL-2 by mitogen stimulated blood lymphocytes. Thus, affected males in this family carry an abnormal gene on their X chromosome that results in a combined immunodeficiency that is distinct from previously reported disorders.

Excellent survival after sibling or unrelated donor stem cell transplantation for chronic granulomatous disease.

BACKGROUND Matched related donor (MRD) hematopoietic stem cell transplantation (HSCT) is a successful treatment for chronic granulomatous disease (CGD), but the safety and efficacy of HSCT from unrelated donors is less certain. OBJECTIVE We evaluated the outcomes and overall survival in patients with CGD after HSCT. METHODS We report the outcomes for 11 children undergoing HSCT from an MRD (n = 4) or an HLA-matched unrelated donor (MUD) (n = 7); 9 children were boys, and the median age was 3.8 years (range, 1-13 years). We treated both X-linked (n = 9) and autosomal recessive (n = 2) disease. Nine children had serious clinical infections before transplantation. The conditioning regimens contained busulfan, cyclophosphamide, cytarabine, or fludarabine according to the donor used. All patients received alemtuzumab (anti-CD52 antibody). Additional graft-versus-host disease (GvHD) prophylaxis included cyclosporine and methotrexate for MUD recipients and cyclosporine and prednisone for MRD recipients. RESULTS Neutrophil recovery took a median of 16 days (range, 12-40 days) and 18 days (range, 13-24 days) for MRD and MUD recipients, respectively. Full donor neutrophil engraftment occurred in 9 patients, and 2 had stable mixed chimerism; all patients had sustained correction of neutrophil oxidative burst defect. Four patients had grade I skin acute GVHD responding to topical treatment. No patient had grade II to IV acute GvHD or chronic GvHD. All patients are alive between 1 and 8 years after HSCT. CONCLUSION For CGD, equivalent outcomes can be obtained with MRD or MUD stem cells, and HSCT should be considered an early treatment option.

Burkitt's lymphoma developing in a 7-year-old boy with hyper-IgE syndrome

We report a case of Burkitts lymphoma developing in a 7-year-old boy with hyper-IgE syndrome. This is the third reported case of malignancy in the hyper-IgE syndrome. The other two cases were an 18-year-old man with Hodgkins disease and a 10-year-old girl with histiocytic lymphoma. The patient developed retroperitoneal Burkitts lymphoma with probable metastasis to the brain. His short life was characterized by recurrent staphylococcal skin, middle ear, and lung infections associated with extremely elevated serum concentrations of IgE. There was also an associated disturbance of bone metabolism with osteoporosis and pathologic fractures and absence of parathormone, findings that have been observed in other patients with hyper-IgE syndrome and other forms of T cell immunodeficiency. At the age of 5 years, inadequate B cell responses to immunization with antigens derived from diphtheria, tetanus, and Haemophilus influenzae type b organisms and with the OX174 bacteriophage were demonstrated in the patient. In his terminal state his in vitro lymphocyte analysis demonstrated findings of anergy. Although the precise immunologic defect in hyper-IgE syndrome is unknown, these cases of associated malignancy stress the role that a completely normal immune system plays in preventing the premature appearance of cancer.