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H D Ochs

Publications and source records attributed to H D Ochs.

At least 109 records · Page 6Linked to original sources
PubMed1995

Long-term hepatic adenovirus-mediated gene expression in mice following CTLA4Ig administration.

Recombinant adenovirus vectors are efficient at transferring genes into somatic tissues but are limited for use in clinical gene therapy by immunologic factors that result in the rapid loss of gene expression and inhibit secondary gene transfer. This study demonstrates that systemic coadministration of recombinant adenovirus with soluble CTLA4Ig, which is known to block co-stimulatory signals between T cells and antigen presenting cells, leads to persistent adenoviral gene expression in mice without long-term immunosuppression. This form of immunotherapy greatly enhances the likelihood that recombinant adenovirus vectors will be useful for human gene therapy.

Abatacept↗
PubMed1995

WASP gene mutations in Wiskott-Aldrich syndrome and X-linked thrombocytopenia.

The WASP gene has been recently cloned from Xp11.23 and shown to be mutated in three patients with the Wiskott-Aldrich syndrome (WAS). We have developed a screening protocol for identifying WASP gene alterations in genomic DNA and have identified a spectrum of novel mutations in 12 additional unrelated families. These missense, nonsense and frameshift mutations involve eight of the 12 exons of the gene. Two mutations creating premature termination codons were associated with lack of detectable mRNA on Northern blots. Four amino acid substitutions, Leu27Phe, Thr48Ile, Val75Met and Arg477Lys, were found in patients with congenital thrombocytopenia and no clinically evident immune defect indicating that the WASP gene is the site for mutations in X-linked thrombocytopenia as well as in WAS. A T-cell line from a WAS patient contained two independent DNA alterations, a constitutional frameshift mutation, also present in peripheral blood leukocytes from the patient, and compensatory splice site mutation unique to the cell line. The distribution of eight missense mutations provides valuable information on amino acids which are essential for normal protein function, and suggests that sites in the first two exons are hot-spots for mutation.

Adolescent↗
PubMed1995

Diminished expression of CD40 ligand by activated neonatal T cells.

CD40 and CD40 ligand (gp39) mediate contact-dependent T-B cell interaction. We determined the expression of CD40 ligand by activated neonatal T cells and the response of neonatal B cells when activated through CD40. Although expression of CD40 ligand peaked simultaneously in both activated adult and neonatal cells, neonatal T cells expressed significantly less CD40 ligand surface protein and mRNA than adult T cells. Activated thymocytes also expressed far less CD40 ligand than adult T cells. Consistent with these results, activated neonatal T cells exhibited less helper function than activated adult T cells. Neonatal T cells primed and restimulated in vitro expressed CD40 ligand in amounts comparable with adult T cells and provided B cell help more effectively. This suggests that the poor expression of CD40 ligand reflects antigenic naiveté rather than an intrinsic defect of neonatal T cells. Neonatal B cells cultured with soluble CD40 ligand (sgp39) and IL-10 produced IgM in amounts comparable with adult cells, but much less IgG and IgA. Nevertheless, neonatal B cells were capable of proliferation and class switching, since sgp39 and IL-4 induced proliferation and IgE production comparable to adult B cells and production of modest amounts of IgG. Together, these results indicate that diminished CD40 ligand expression, along with decreased production of lymphokines, may be responsible, at least in part, for the transient immunodeficiency observed in human neonates.

Adult↗
PubMed1995

Neutrophil adhesion in leukocyte adhesion deficiency syndrome type 2.

We have previously reported a newly discovered congenital disorder of neutrophil adhesion, leukocyte adhesion deficiency syndrome type 2 (LAD II). The clinical manifestations of this syndrome are similar to those seen in the classic leukocyte adhesion deficiency syndrome, now designated type 1 (LAD I), but the two syndromes differ in the molecular basis of their adhesion defects. LAD I is caused by a deficiency in the CD18 integrin adhesion molecules while LAD II patients are deficient in expression of sialyl-Lewis X (SLeX), a carbohydrate ligand for selectins. In this report we demonstrate that neutrophils from a LAD II patient bind minimally or not at all to recombinant E-selectin, purified platelet P-selectin, or P-selectin expressed on histamine-activated human umbilical vein endothelial cells, but have normal levels of L-selectin and CD11b/CD18 integrin, and adhere to and migrate across endothelium when CD11b/CD18 is activated. We compare LAD I and LAD II patient neutrophil function in vitro, demonstrating that integrin and selectin adhesion molecules have distinct but interdependent roles in neutrophil adhesion during an inflammatory response.

CD11 Antigens↗
PubMed1994

Structural basis for chromosome X-linked agammaglobulinemia: a tyrosine kinase disease.

X-linked agammaglobulinemia (XLA) is a hereditary defect of B-cell differentiation in man caused by deficiency of Bruton tyrosine kinase (BTK). A three-dimensional model for the BTK kinase domain, based on the core structure of cAMP-dependent protein kinase, was used to interpret the structural basis for disease in eight independent point mutations in patients with XLA. As Arg-525 of BTK has been thought to functionally substitute for a critical lysine residue in protein-serine kinases, the mutation Arg-525-->Gln was studied and found to abrogate the tyrosine kinase activity of BTK. All of the eight mutations (Lys-430-->Glu, Arg-520-->Glu, Arg-525-->Gln, Arg-562-->Pro, Ala-582-->Val, Glu-589-->Gly, Gly-594-->Glu, and Gly-613-->Asp) were located on one face of the BTK kinase domain, indicating structural clustering of functionally important residues.

Adenosine Triphosphate↗
PubMed1994

In vivo neutrophil and lymphocyte function studies in a patient with leukocyte adhesion deficiency type II.

We investigated in vivo neutrophil and lymphocyte function in a patient who lacks Sialyl-Lewis-X, a ligand for the selectin family of leukocyte adhesion molecules (leukocyte adhesion deficiency II, LAD II). As assessed by skin chamber and skin window techniques, in vivo chemotaxis of neutrophils was markedly impaired (less than 6% of normal values). A marginal pool was present as determined by an increase in circulating neutrophils after epinephrine injection and calculated recovery of infused radiolabeled autologous neutrophils. Kinetic studies showed a reduced half-life of 3.2 hours (normal 7 hours) and markedly increased turnover rate (cells/kg/d) of approximately eight times the normal value. A normal antibody response to the T-cell-dependent antigen bacteriophage phi X174 showed that T/B-cell interaction is not affected in LAD II. These findings provide direct evidence that the selectin family and its ligands play an important role in neutrophil function.

Antibody Formation↗
PubMed1994

Isolation of a novel gene mutated in Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive immunodeficiency characterized by eczema, thrombocytopenia, and recurrent infections. Linkage studies have placed the gene at Xp11.22-p11.23. We have isolated from this interval a novel gene, WASP, which is expressed in lymphocytes, spleen, and thymus. The gene is not expressed in two unrelated WAS patients, one of whom has a single base deletion that produces a frame shift and premature termination of translation. Two additional patients have been identified with point mutations that change the same arginine residue to either a histidine or a leucine. WASP encodes a 501 amino acid proline-rich protein that is likely to be a key regulator of lymphocyte and platelet function.

Amino Acid Sequence↗
PubMed1994

Deletion within the Src homology domain 3 of Bruton's tyrosine kinase resulting in X-linked agammaglobulinemia (XLA).

The gene responsible for X-linked agammaglobulinemia (XLA) has been recently identified to code for a cytoplasmic tyrosine kinase (Bruton's agammaglobulinemia tyrosine kinase, BTK), required for normal B cell development. BTK, like many other cytoplasmic tyrosine kinases, contains Src homology domains (SH2 and SH3), and catalytic kinase domain. SH3 domains are important for the targeting of signaling molecules to specific subcellular locations. We have identified a family with XLA whose affected members have a point mutation (g-->a) at the 5' splice site of intron 8, resulting in the skipping of coding exon 8 and loss of 21 amino acids forming the COOH-terminal portion of the BTK SH3 domain. The study of three generations within this kinship, using restriction fragment length polymorphism and DNA analysis, allowed identification of the mutant X chromosome responsible for XLA and the carrier status in this family. BTK mRNA was present in normal amounts in Epstein-Barr virus-induced B lymphoblastoid cell lines established from affected family members. Although the SH3 deletion did not alter BTK protein stability and kinase activity of the truncated BTK protein was normal, the affected patients nevertheless have a severe B cell defect characteristic for XLA. The mutant protein was modeled using the normal BTK SH3 domain. The deletion results in loss of two COOH-terminal beta strands containing several residues critical for the formation of the putative SH3 ligand-binding pocket. We predict that, as a result, one or more crucial SH3 binding proteins fail to interact with BTK, interrupting the cytoplasmic signal transduction process required for B cell differentiation.

Adult↗
PubMed1994

Costimulation through CD28 enhances T cell-dependent B cell activation via CD40-CD40L interaction.

Changes in T cell helper function were analyzed when anti-CD3-activated T cells were costimulated with mAbs to the CD28 receptor (anti-CD28). T cell-dependent B cell growth and differentiation were consistently augmented if anti-CD3 stimulated-T cells were simultaneously activated with anti-CD28. Although anti-CD28 enhanced IL-2 and IL-4 production, it did not increase B cell responses solely by augmenting production of soluble lymphokines. Anti-CD28 costimulation induced increases on T cells of CD40 ligand (CD40L), known to promote B cell proliferation and Ig secretion. Because anti-CD28 promoted T cell helper functions and expression of CD40L, we examined the dependence for CD40L during T cell-dependent B cell responses. Although soluble CD40 fusion proteins only partially inhibited T cell-dependent B cell activation, we found a strict requirement for CD40L expression at initiating B cell responses. Both CD40L expression and T cell help were blocked by cyclosporin A after TCR cross-linking, and, unlike T cell proliferation, both remained cyclosporin A sensitive during CD28 costimulation. In addition, anti-CD28 could not compensate for the T cell helper deficiency of hyper IgM syndrome patients who lack functional CD40L. Thus, anti-CD28-induced T cell help is delivered via a CD40L-dependent process. The fact that cross-linking CD40 on B cells promotes expression of the B7/BB-1 ligand for CD28 suggest T and B interactions may have a reciprocal amplification mechanism.

Antigens, CD↗
PubMed1994

CD40 ligand expression is defective in a subset of patients with common variable immunodeficiency.

Common variable immunodeficiency (CVI) is characterized by hypogammaglobulinemia and recurrent bacterial infections due to failure of CVI B cells to differentiate in vivo into immunoglobulin-secreting plasma cells. We hypothesized that T-cell dysfunction resulting in abnormal contact-mediated B-cell activation may play a prominent role in the failure of CVI B cells to produce specific antibody. We have previously shown that B-cell proliferation and IgE production after stimulation with anti-CD40 and interleukin (IL) 4 were normal in 22 CVI patients evaluated, indicating that CVI B cells respond to signals delivered via CD40. Here we report that CD40 ligand (gp39) mRNA expression by activated lymphocytes from CVI patients (n = 31) as a group was significantly depressed (P < 0.0001) compared with normal controls (n = 32). gp39 mRNA expression by activated lymphocytes from 13 CVI patients fell below the normal control range. T-cell surface expression of functional gp39 protein was correspondingly low in those patients with gp39 mRNA levels below normal control range and normal in patients with gp39 mRNA levels within normal control range. In CVI patients as a group, gp39 mRNA levels correlated with IL-2 mRNA levels (P < 0.002, r = 0.6) and production (P < 0.001, r = 0.7) but not with gene expression or production of other lymphokines evaluated, suggesting an as-yet-undetermined association between gp39 and IL-2 gene regulation. Of the 13 patients whose activated T cells exhibited gp39 mRNA expression below the normal control range, 2 had normal T-cell-derived lymphokine production, whereas the remaining 11 exhibited broader T-cell dysfunction, resulting in IL-2 deficiency, and in some patients deficient production of other lymphokines as well, reflecting a heterogeneity in the underlying mechanisms leading to depressed gp39 expression in these patients. The observation that both gene and surface expression of gp39 by activated T cells is depressed in a subgroup of CVI patients suggests that inefficient signaling via CD40 may be responsible, in part, for failure of B-cell differentiation in these patients.

Adolescent↗
PubMed1994

A new RFLP marker, SP282, at the btk locus for genetic analysis in X-linked agammaglobulinaemia families.

X-linked agammaglobulinaemia is an inherited recessive disease in which the primary defect lies in the failure of pre-B cells to develop into mature circulating B cells, due to a defective B-cell cytoplasmic tyrosine kinase (btk). For this study we introduced a new RFLP marker, SP282, which is tightly linked to the XLA locus. In conjunction with the marker DXS178, SP282 was used to identify a carrier female and predict her male offspring to be normal. Subsequently the fetus was shown to have a normal number of circulating B cells, and at 2.5 years of age, the non-affected phenotype of the child was confirmed.

Agammaglobulinemia↗
PubMed1994

Effect of IL-2 on immunoglobulin production by anti-CD40-activated human B cells: synergistic effect with IL-10 and antagonistic effect with IL-4.

Activation of B cells by anti-CD40 provides an excellent model to investigate the direct effect of various cytokines on Ig production. Using this culture system, we examined the effect of IL-2 alone or in combination with other cytokines. IL-2 alone had only a moderate effect on Ig production by anti-CD40-activated B cells if compared with the effect of IL-10. However, IL-2 significantly augmented the synthesis of IgM, IgA, and IgG, including all IgG subclasses by anti-CD40-activated B cells cultured in the presence of IL-10. Both IgD- and IgD+ B cells showed an increase of IL-10-induced Ig production if IL-2 was added to the culture. The addition of IL-2 also increased immunoglobulin synthesis by anti-CD40/IL-10-activated B cells from patients with common variable immunodeficiency (CVI) and defective IL-2 production, suggesting that in a subgroup of CVI patients the IL-2 deficiency may contribute to the observed hypogammaglobulinemia. In contrast, the addition of IL-2 had a suppressive effect on IgE and IgG4 production by B cells cultured in the presence of anti-CD40 and IL-4. These data demonstrate that IL-2 plays an active role in the regulation of Ig production via CD40 by anti-CD40-activated B cells.

Adult↗
PubMed1994

Isolation of cosmid and cDNA clones in the region surrounding the BTK gene at Xq21.3-q22.

A regional physical and transcription map involving yeast artificial chromosomes (YACs), cosmids, and cDNAs has been constructed for Xq21.3-q22 around the gene BTK (formerly atk or BPK) defective in X-linked agammaglobulinemia (XLA). With a positional cloning strategy employing direct cDNA selection, novel cDNAs were found to cluster in the region of approximately 100 kb flanking the XLA and alpha-galactosidase A loci. While these widely expressed transcripts are in the area known to contain CpG islands, a less evolutionarily conserved gene, located more than 130 kb distal of DXS178, maps to cosmid clones that could not be digested with rare-cutting restriction enzymes. The presence of transcribed sequences flanking the BTK allowed us to investigate their involvement in complex XLA phenotypes. Southern blot analysis using cDNA clones isolated from this region permitted us to exclude a contiguous deletion syndrome as an underlying defect in three patients with XLA and associated growth hormone deficiency. A single XLA patient with torsion dystonia and cosegregating X-linked deafness has been found with a deletion in the 3' part of BTK extending centromerically into the flanking expressed sequence DXS1274E. This suggests a possible involvement of the DXS1274E in this phenotype. The GenBank accession numbers for novel cDNA sequences are as follows: DXS1269E (L20773), DXS1271E (UO1923), DXS1273E (UO1925), and DXS1274E (UO1922).

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1994

The role of CD40L (gp39)/CD40 in T/B cell interaction and primary immunodeficiency.

The interaction between the CD40 ligand (gp39), expressed by activated T cells, and CD40, constitutively expressed by B cells, is critical for an effective antibody response to T cell dependent antigens. Patients with X-linked hyper IgM (HIM) syndrome fail to express a functional CD40 ligand due to a mutation within the gene for gp39. As a direct consequence, HIM patients, when immunized with T dependent antigens, produce only small amounts of IgM antibody without the development of immunologic memory, amplification and switch from IgM to IgG. Mutations affecting the gene for the HIM syndrome are localized throughout the coding region of gp39 and consist predominantly of point mutations. The resulting amino acid substitutions interfere directly with the receptor binding site or lead to stop codons or deletions secondary to splice site mutations. Expression of gp39 by activated T cells from patients with common variable immunodeficiency (CVI) is low in approximately half of the patients and is associated with depressed expression of IL-2. These findings suggest that inefficient signaling via CD40 may be responsible in part for failure of B cell differentiation in CVI.

Antigens, CD↗
PubMed1994

Heterogeneity of phenotype in two siblings with adenosine deaminase deficiency.

Adenosine deaminase (ADA) deficiency is the cause of about one third of the autosomal recessively inherited cases of severe combined immunodeficiency. Disease severity in ADA deficiency is variable, presumably related in part to heterogeneity in the genotypes causing the disease. We now report on two children in a single family with ADA deficiency who presented with distinct clinical courses. One child presented with severe immunodeficiency and recurrent infections that led to the diagnosis of severe combined immunodeficiency and ADA deficiency at 7 months of age. The older child, who was diagnosed at 3 years of age (after the diagnosis of the younger child), did not have a history of serious or opportunistic infections. Although she was lymphopenic, immune responsiveness was intact, in terms of antibody production, delayed-type hypersensitivity, and in vitro T-cell function. The difference in clinical course in these two siblings is an important observation and demonstrates that the phenotypic expression of ADA deficiency can vary within a family, even in a situation in which protective isolation from infectious pathogens was not a factor in causing the milder course. These observations indicate that expression of disease severity in ADA deficiency may depend to a significant degree on environmental factors and/or on heterogeneity at other genetic loci, which may regulate or modify the expression of the ADA gene or the activity of its product. Furthermore, these observations highlight the importance of recognizing patients with ADA deficiency who present with less severe disease and support the impression that functional immunity in patients with the "late-onset" form of ADA deficiency can deteriorate over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1994

Hepatitis C virus transmission by intravenous immunoglobulin.

The polymerase chain reaction was used to detect hepatitis C virus infection in patients who had previously been reported to have developed non-A, non-B hepatitis after intravenous immunoglobulin infusion. Of the 33 patients with intravenous immunoglobulin associated non-A, non-B hepatitis studied, HCV RNA could be detected in 15 out of 17 patients (88%) who were HCV RNA negative prior to the development of non-A, non-B hepatitis after implicated intravenous immunoglobulin batches. Similarly, eight out of nine patients (89%) in whom no sample was available for polymerase chain reaction testing prior to intravenous immunoglobulin therapy, had detectable HCV RNA after intravenous immunoglobulin therapy with intravenous immunoglobulin batches implicated in non-A, non-B hepatitis transmission. Two of the three intravenous immunoglobulin preparations implicated in non-A, non-B hepatitis transmissions that were available for polymerase chain reaction testing also had detectable HCV RNA, confirming that hepatitis C virus is the implicated virus in intravenous immunoglobulin-associated non-A, non-B hepatitis.

Hepacivirus↗