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Biomedical subjects

C M Roifman

Publications and source records attributed to C M Roifman.

At least 19 recordsLinked to original sources
PubMed2006

Bone marrow transplantation for cartilage-hair-hypoplasia.

The association of cartilage hair hypoplasia (CHH) with severe combined immunodeficiency (SCID) has been known for more than three decades. Bone marrow transplantation (BMT) remains the only effective treatment that might cure SCID. Surprisingly little has been reported on the experience with BMT in CHH. We report here survival and long-term reconstitution of immunity after BMT in three patients with CHH. Regardless of whether a related human leukocyte antigen-matched or unrelated matched donors were used as the source of BMT, all patients are alive and well 5-20 years after BMT. Engraftment appears robust with most cells of donors origin. Repeated evaluation of the immune system showed normal cellular and humoral immunity. Our results should encourage the use of BMT in patients with CHH who have profound immunodeficiency.

Bone Marrow Transplantation↗
PubMed2003

A novel syndrome of combined immunodeficiency, autoimmunity and spondylometaphyseal dysplasia.

We describe here four patients who appear to have similar clinical and immunological features which constitute a novel syndrome. The patients present with short stature owing to spondylometaphyseal dysplasia and with severe infections as the result of a combined humoral and cellular immune deficiency. Presumably because of dysregulation of the immune system, all patients also developed autoimmune manifestations.

Adolescent↗
PubMed2001

Two novel mutations in a purine nucleoside phosphorylase (PNP)-deficient patient.

Purine nucleoside phosphorylase (PNP) deficiency is a rare autosomal recessive disease, which presents clinically as severe combined immunodeficiency (SCID). We report here two novel mutations in the PNP gene that result in SCID phenotype, in a single patient. The maternal-derived allele carries a C to T transition in exon 2 resulting in a premature stop codon at amino acid 57. The paternal-derived mutation is a G to A transition at position +1 in intron 3, causing a complete skipping of exon 3 and a reading frameshift at the exon 2-exon 4 junction. The predicted polypeptide encoded by the aberrantly spliced mRNA terminates prematurely after only 89 amino acids. Both mutations predict severely truncated proteins resulting in a complete deficiency of PNP enzymatic activity, yet the development of profound immunodeficiency in this patient is greatly delayed.

Amino Acid Sequence↗
PubMed2001

Immune function in patients with Shwachman-Diamond syndrome.

Shwachman-Diamond syndrome (SDS) is an inherited multisystem disorder characterized by exocrine pancreatic dysfunction and varying degrees of cytopenia. In addition, various immunological abnormalities have been noted. To clarify the issue of immunological competence or incompetence in SDS, we prospectively studied immune function in 11 patients with SDS. Seven suffered from recurrent bacterial infections and six from recurrent viral infections. Varying degrees of impairment were readily identified. All patients had neutropenia; total lymphocyte counts, however, were normal in all except one patient. Nine patients had B-cell defects comprising one or more of the following abnormalities: low IgG or IgG subclasses, low percentage of circulating B lymphocytes, decreased in vitro B-lymphocyte proliferation and a lack of specific antibody production. Seven out of nine patients studied had at least one T-cell abnormality comprising a low percentage of total circulating T lymphocytes or CD3+/CD4+ cell subpopulations or decreased in vitro T-lymphocyte proliferation. Five out of six patients studied had decreased percentages of circulating natural killer cells. Moreover, neutrophil chemotaxis was significantly low in all the patients studied. These data point to a major immunodeficiency component in SDS that places patients at heightened risk of infections, even if neutrophil numbers are protective. This finding broadens the definition of the syndrome substantially: it suggests that the SDS marrow defect occurs at the level of an early haematological-lymphocytic stem cell or that a combined marrow and thymic stromal defect accounts for the aberrant function of haematopoietic and lymphopoietic lineages.

Adolescent↗
PubMed2001

Signal-transduction defects in T cells.

In conclusion, multiple receptors and signal transduction cascades influence T-cell function and fate. During the past few years many of these important aspects of T-cell biology were identified. The complexity of the various signaling pathways has made appreciation of their clinical significance difficult. One way of studying the function of these molecules is to create mice deficient of these components. However, frequently the murine phenotype is far from reflecting the homologous human deficiency. It is therefore beneficial to define the human immunodeficiencies in order to understand the role of a certain signaling molecule in humans. Further, mutations that result in partial deficiencies may result in a different phenotype from null mutations. This information may aid in improving structure/function analysis of these signaling components.

Humans↗
PubMed2000

A partial deficiency of interleukin-7R alpha is sufficient to abrogate T-cell development and cause severe combined immunodeficiency.

Both in vitro and in vivo studies established that interleukin 7 (IL-7) is essential for differentiation of immature T cells and B cells but not natural killer (NK) cells in the mouse. In humans, although both T-cell and B-cell progenitors express the functional IL-7 receptor that consists of IL-7R alpha and the gamma common (gamma c) chain, this lymphocyte receptor system is critical for T lineage but not for B lineage development. Indeed, complete gamma c deficiency like IL-7R alpha deficiency results in the arrest of T-cell but not B-cell development (T(-)B(+) SCID). However, partial deficiency of gamma c caused by missense mutations results in a T(+)B(+) phenotype and a delay of clinical presentation. It was therefore plausible to assume that partial deficiency of IL-7R alpha, like partial gamma c deficiency may lead to a milder clinical and immunologic phenotype. A P132S mutation in the IL-7R alpha was identified in 3 patients with severe combined immunodeficiency (SCID) within an extensively consanguineous family. Substitution of proline with serine in the extracellular portion of IL-7R alpha did not affect IL-7R alpha messenger RNA (mRNA) and protein expression, but severely compromised affinity to IL-7, resulting in defective signal transduction. In response to IL-7 stimulation, Jak-3 phosphorylation was markedly reduced in both patient cells as well as in COS cells reconstituted with mutant IL-7R alpha. Surprisingly, this partial deficiency of IL-7R alpha resulted in a severe phenotype, including markedly reduced circulating T cells while sparing B-cell numbers similar to gamma c chain deficiency. However, unlike the previously reported cases, serum immunoglobulins were virtually absent. Further, unlike gamma c deficiency, NK cell numbers and function was preserved. Despite the partial deficiency, clinical presentation was indistinguishable from a complete gamma c deficiency, including severe and persistent viral and protozoal infections and failure to thrive. Unlike partial gamma c deficiency, a partial deficiency of IL-7R alpha results in an arrest of T-cell development, leading to typical severe combined immunodeficiency. This underscores the critical role of IL-7R alpha chain in the differentiation of T cells. (Blood. 2000;96:2803-2807)

Agammaglobulinemia↗
PubMed2000

Mitochondrial basis for immune deficiency. Evidence from purine nucleoside phosphorylase-deficient mice.

We generated purine nucleoside phosphorylase (PNP)-deficient mice to gain insight into the mechanism of immune deficiency disease associated with PNP deficiency in humans. Similar to the human disease, PNP deficiency in mice causes an immunodeficiency that affects T lymphocytes more severely than B lymphocytes. PNP knockout mice exhibit impaired thymocyte differentiation, reduced mitogenic and allogeneic responses, and decreased numbers of maturing thymocytes and peripheral T cells. T lymphocytes of PNP-deficient mice exhibit increased apoptosis in vivo and higher sensitivity to gamma irradiation in vitro. We propose that the immune deficiency in PNP deficiency is a result of inhibition of mitochondrial DNA repair due to the accumulation of dGTP in the mitochondria. The end result is increased sensitivity of T cells to spontaneous mitochondrial DNA damage, leading to T cell depletion by apoptosis.

Animals↗
PubMed2000

Matched unrelated bone marrow transplantation for combined immunodeficiency.

Bone marrow transplantation (BMT) from siblings is the treatment of choice for severe combined immunodeficiency (SCID). The objective of this study was to evaluate the efficiency of BMT from matched unrelated donors (MUD) in congenital immunodeficiencies when a sibling donor is unavailable. Sixteen consecutive patients with SCID (n = 9) and CID (n= 7), were referred for an unrelated donor search. Acceptable donors were found for all patients. Fifteen patients received busulfan and cyclophosphamide pretransplant conditioning. One patient had an early loss of graft and was reconditioned using cyclophosphamide and total body irradiation. The graft-versus-host disease (GVHD) prophylaxis used was methylprednisolone, cyclosporin A with or without methotrexate. Neutrophil engraftment was rapid and was achieved in all patients within a mean of 15.4 days. Only 13 episodes of fever were recorded shortly after BMT. GVHD of grade II or more was apparent in 2/9 (22%) of SCID patients and in 4/7 (57%) of CID patients. Overall survival was 75% with a mean follow-up of 47.4 months (range 18-101). Six out of nine SCID patients (67%) and 6/7 (86%) of CID patients are alive and well. Eleven patients had normal humoral immunity, and cell-mediated immunity as measured by flow cytometry and mitogenic responses, was intact in all patients. Intradermal candida skin test was positive in 9/10 patients tested. We conclude that BMT from MUD results in rapid engraftment and is therefore associated with a low rate of infection contributing to the improved survival rate. The protocol used is especially favorable for patients with combined immunodeficiency.

Anti-Bacterial Agents↗
PubMed2000

Haemophagocytic lymphohistiocytosis in X-linked severe combined immunodeficiency.

Haemophagocytic lymphohistiocytosis (HLH) is characterized by destruction of haematopoietic elements, and is associated with a variety of manifestations including immune abnormalities. We describe an infant with HLH who had no evidence of infection or malignancy. He had markedly reduced natural killer (NK) and T-cell numbers and mitogen responses, consistent with severe combined immune deficiency. Western blot and flow cytometry analyses revealed an absence of interleukin (IL)-2 receptor gamma (gamma common) chain expression and a transition (C --> T) at nucleotide 684 in the gamma common gene. This novel case highlights the need for a thorough evaluation of immunological phenotype and genotype in patients with HLH.

Blotting, Western↗
PubMed2000

Human IL-2 receptor alpha chain deficiency.

Profound cellular immunodeficiency occurs as the result of mutations in proteins involved in both the differentiation and function of mature lymphoid cells. We describe here a novel human immune aberration arising from a truncation mutation of the IL-2 receptor alpha chain (CD25), a subunit of the tripartite high-affinity receptor for IL-2. Decreased numbers of peripheral T cells displaying abnormal proliferation but normal B-cell development characterize this immunodeficiency. Extensive lymphocytic infiltration of tissues, including lung, liver, gut, and bone, is observed, accompanied by tissue atrophy and inflammation. Although mature T cells are present, the absence of CD25 does affect the differentiation of thymocytes. Although displaying normal development of CD2, CD3, CD4, and CD8 expression, CD25-deficient cortical thymocytes do not express CD1. Furthermore, they fail to down-regulate levels of bcl-2 and, subsequently, apoptosis in the thymus is markedly reduced, resulting in expansion of autoreactive clones in multiple tissues.

Amino Acid Sequence↗
PubMed1999

Cloning and characterization of a lymphoid-specific, inducible human protein tyrosine phosphatase, Lyp.

Protein tyrosine phosphatases act in conjunction with protein kinases to regulate the tyrosine phosphorylation events that control cell activation and differentiation. We have isolated a previously undescribed human phosphatase, Lyp, that encodes an intracellular 105-kD protein containing a single tyrosine phosphatase catalytic domain. The noncatalytic domain contains four proline-rich potential SH3 domain binding sites and an NXXY motif that, if phosphorylated, may be recognized by phosphotyrosine binding (PTB) domains. Comparison of the Lyp amino acid sequence with other known proteins shows 70% identity with the murine phosphatase PEP. The human Lyp gene was localized to chromosome 1p13 by fluorescence in situ hybridization analysis. We also identified an alternative spliced form of Lyp RNA, Lyp2. This isoform encodes a smaller 85-kD protein with an alternative C-terminus. The lyp phosphatases are predominantly expressed in lymphoid tissues and cells, with Lyp1 being highly expressed in thymocytes and both mature B and T cells. Increased Lyp1 expression can be induced by activation of resting peripheral T lymphocytes with phytohemagglutinin or anti-CD3. Lyp1 was found to be constitutively associated with the proto-oncogene c-Cbl in thymocytes and T cells. Overexpression of lyp1 reduces Cbl tyrosine phosphorylation, suggesting that it may be a substrate of the phosphatase. Thus, Lyp may play a role in regulating the function of Cbl and its associated protein kinases.

Alternative Splicing↗
PubMed1999

Anaphylaxis and epinephrine auto-injector training: who will teach the teachers?

BACKGROUND: Anaphylaxis is the most urgent clinical immunologic event. Effective treatment is best achieved by administration of epinephrine. Accidental exposure to the responsible allergen is the most common cause of anaphylaxis, and because it could be fatal within minutes, epinephrine in preloaded syringes and auto-injectors has been introduced. In our experience patients and medical personnel are not familiar with the use of this device. OBJECTIVE: We sought to assess community-based professionals' knowledge of epinephrine auto-injector use and their ability to educate patients. METHODS: Study participants consisted of a medical convention's delegates and emergency department personnel in metropolitan Toronto, as well as pharmacists of the target hospitals and retail pharmacists. Research assistants approached eligible professionals to fill out a questionnaire and demonstrate their ability to use a standard placebo auto-injector trainer. RESULTS: A total of 122 professionals (composed of emergency physicians, family practitioners, and pediatricians) consented to participate in this study. The majority of participants (81%) did not have a placebo trainer to educate their patients; 76% did not know the 2 available dose strengths. To provide instructions and reinforcement, physicians clearly must have the necessary skills and knowledge, yet only 25% of the study participants were able to demonstrate the 3 steps of injection correctly. CONCLUSION: Our study highlights a specific and important deficiency in medical professionals' care of patients at risk for anaphylaxis. The results challenge the current methods of educating professionals, as well as patients, when prescribing or using epinephrine auto-injectors. Clearly a new approach to educating and maintaining such skills is required.

Anaphylaxis↗
PubMed1999

Antibody deficiency, growth retardation, spondyloepiphyseal dysplasia and retinal dystrophy: a novel syndrome.

The clinical and laboratory combination of recurrent infections due to antibody deficiency, spondyloepiphyseal dysplasia, growth retardation and retinal dystrophy is novel. Four patients with strikingly similar phenotypes from three different families of diverse genetic backgrounds are described, suggesting a similar underlying genotype. Increased awareness of this syndrome will hopefully lead to the description of a larger number of affected individuals, which ultimately might be critical for its genetic characterization.

Abnormalities, Multiple↗
PubMed1999

Long-term remission for disseminated Mycobacterium avium-intracellulare complex associated with antibody deficiency.

Mycobacterium avium-intracellulare (MAI) is a ubiquitous organism with limited virulence in the immunocompetent host. Disseminated disease is associated with a high mortality rate. Except for localized cervical adenitis, MAI disease is rare in immunocompetent children. We report a child with antibody deficiency (dysgammaglobulinemia) and disseminated MAI infection, in whom complete, long-term remission was attained with multiple antimycobacterial therapy. The patient presented with progressive cervical lymphadenopathy and hepatomegaly at 7 years of age. A lymph node biopsy showed acid-fast bacilli and granulomas. Despite a transient response to conventional antituberculous therapy, including isoniazid and rifampin, his symptoms progressed. Cultures from blood, bone marrow, spleen, and cervical lymph node tissues revealed an MAI organism. Subsequent treatment using a combination of clarithromycin, amikacin, and ethambutol for 16 months resolved clinical symptoms, and subsequent blood culture results became negative. By the time of this report, the patient has been disease-free for 4 years. Multiple-drug therapy is promising for the treatment of MAI in children with antibody deficiency; however, the selection of antiinfective drugs should include a member of the newer macrolide family. acquired immunodeficiency syndrome, clarithromycin, dysgammaglobulinemia, Mycobacterium avium-intracellulare, treatment.

Antitubercular Agents↗
PubMed1999

Anaphylactic reaction to oral cefaclor in a child.

Adverse drug reactions are a common clinical problem. It has been estimated that 6% to 15% of hospitalized patients experience some sort of adverse drug reaction. Clinical manifestations of adverse drug reactions include skin rash; a serum sickness-like reaction; drug fever; pulmonary, hepatic, and renal involvement; and systemic anaphylaxis. Many of these adverse events are not immunologically mediated. Actual allergic or immunologic drug reactions probably account for <25% of adverse drug reactions overall. Antibiotics are one of the major contributors to drug hypersensitivity. Cefaclor, an oral second-generation cephalosporin with a beta-lactam ring, is used against various infectious diseases of the respiratory tract, especially in children. Several cases of cefaclor hypersensitivity have been reported. The most common presentations are either erythematous or papular eruptions, although serum sickness-like reactions have also been described. Anaphylactic reactions, although rare, have been observed in adults. Here we report a case of anaphylactic reaction to cefaclor in a 21/2-year-old patient.

Administration, Oral↗
PubMed1998

Cloning and characterization of the human homolog of mouse Jak2.

Members of the Jak family play a critical role in signal transduction mediated by cytokine and hormone receptors. In this study, we report the cloning and characterization of human Jak2. The predicted amino acid sequence shows 91% homology to the described murine Jak2, but with a significant difference in the extreme C-terminal sequence. Using the human cDNA as a probe, we localized the gene for human Jak2 to chromosome 9p23-24. Human Jak2 mRNA is highly expressed in the spleen, lymph nodes, and peripheral blood lymphocytes (PBLs). A polyclonal antibody raised against the unique C-terminus of human Jak2 was used to characterize Jak2 protein. Levels of Jak2 protein expression increased significantly in mitogen- and anti-IgM-stimulated B cells and to a lesser degree in activated T cells. In addition, high levels of Jak2 protein were detected in pre-B leukemia cells.

Amino Acid Sequence↗