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Biomedical subjects

D A Carson

Publications and source records attributed to D A Carson.

355 records · Page 20Linked to original sources
PubMed1977

Lymphospecific toxicity in adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency: possible role of nucleoside kinase(s).

Inherited deficiencies of the enzymes adenosine deaminase (adenosine aminohydrolase; EC 3.5.4.4) and purine nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyltransferase; EC 2.4.2.1) preferentially interfere with lymphocyte development while sparing most other organ systems. Previous experiments have shown that through the action of specific kinases, nucleosides can be "trapped" intracellularly in the form of 5'-phosphates. We therefore measured the ability of newborn human tissues to phosphorylate adenosine and deoxyadenosine, the substrate of adenosine deaminase, and also inosine, deoxyinosine, guanosine, and deoxyguanosine, the substrates of purine nucleoside phosphorylase. Substantial activities of adenosine kinase were found in all tissues studied, while guanosine and inosine kinases were detected in none. However, the ability to phosphorylate deoxyadenosine, deoxyinosine, and deoxyguanosine was largely confined to lymphocytes. Adenosine deaminase, but not purine nucleoside phosphorylase, showed a similar lymphoid predominance. Other experiments showed that deoxyadenosine, deoxyinosine, and deoxyguanosine were toxic to human lymphoid cells. The toxicity of deoxyadenosine was reversed by the addition of deoxycytidine, but not uridine, to the culture medium. Based upon these and other experiments, we propose that in adenosine deaminase and purine nucleoside phosphorylase deficiency, toxic deoxyribonucleosides produced by many tissues are selectively trapped in lymphocytes by phosphorylating enzyme(s).

Adenosine Deaminase↗
PubMed1977

Radioimmunoassay of IgG and IgM rheumatoid factors reacting with human IgG.

Although IgG rheumatoid factor may play a central role in the pathogenesis of rheumatoid arthritis, previously there have been no precise methods for its specific measurement in serum and synovial fluid. This paper describes a solid phase radioimmunoassay for the independent quantification of IgM and IgG rheumatoid factor reacting with the Fc fragment of human IgG. As measured by this assay, serum IgG rheumatoid factor levels differed significantly between patients with seropositive and seronegative rheumatoid arthritis and normal control subjects. In addition, several sera and joint fluids from patients with seropositive rheumatoid arthritis, even without vasculitis, were shown by gel chromatography to have acid-dissociable complexes of IgG rheumatoid factor suggestive of IgG-IgG dimer or trimer formation.

Alkylation↗
PubMed1977

Quantitative immunoassay of adenosine deaminase in combined immunodeficiency disease.

We have developed a quantitative immunoassay for the measurement of human adenosine deaminase that requires neither purified enzyme nor monospecific antibody. With this technique, cultured fibroblasts from three immunodeficient patients were shown to contain adenosine deaminase as detected both catalytically and immunochemically. In one patient the level of immunoreactive enzyme exceeded the amount of catalytically active adenosine deaminase, suggesting a structural alteration in the enzyme molecule.

Adenosine Deaminase↗
PubMed1976

Effect of adenosine deaminase inhibition upon human lymphocyte blastogenesis.

The biochemical mechanisms by which a genetically determined deficiency of adenosine deaminase leads to immunodeficiency are still poorly understood and prompted this study. We have examined the effects of the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride (EHNA) upon the response of human peripheral blood mononuclear cells to the mitogen concanavalin A (Con A). Cells isolated from normal volunteers were incubated in microtiter plates in the presence of various inhibitors, and the incorporation of tritrated thymidine or leucine into macromolecular material was measured after 64 h. EHNA at a concentration of 0.3 muM, which inhibited 90% of the adenosine deaminase (ADA) activity in a mononuclear preparation, impaired the incorporation of tritrated leucine into protein; 100 muM EHNA was the minimal concentration that inhibited thymidine uptake. The addition of 15 muM adenosine or 10 muM cyclic AMP to Con A-stimulated lymphocytes inhibited leucine uptake, while millimolar concentrations were required to inhibit thymidine uptake. Lower doses of adenosine and cyclic AMP stimulated thymidine incorporation. The inhibition of thymidine uptake observed with millimolar concentrations of adenosine was independent of the type of mitogen (pokeweed or Con A), the concentration of mitogen, or the medium used, but could be increased if the cells were cultured in a serum with reduced levels of adenosine deaminase. Washout experiments failed to demonstrate a critical period early in immune induction during which adenosine exerted its inhibitory effects. Noninhibitory doses of EHNA potentiated the effects of adenosine and cyclic AMP on leucine and thymidine uptake. EHNA at a concentration of 50 muM also potentiated the inhibitory effects on thymidine uptake of dibutyryl cyclic AMP, butyric acid, norepinephrine, and isoproterenol, but not theophylline. When mitogenesis was assayed by leucine incorporations, no synergy between EHNA and these compounds was apparent. Uridine relieved to some extent the inhibition of blastogenesis produced by adenosine and cyclic AMP, but not by dibutyryl cyclic AMP, norepinephreine, isoproterenol, or theophylline. Neither uridine alone nor uridine plus adenosine protected lymphocytes from the inhibitory effects of EHNA.

Adenosine↗
PubMedDate not supplied

Relative reactivities of rheumatoid factors in serum and cells. Evidence for a selective deficiency in serum rheumatoid factor.

Investigations of rheumatoid factors by a hemolytic plaque forming cell assay of blood lymphocytes with sensitized sheep cells have suggested that the rheumatoid factors released from the cells have higher affinities for human IgG than do the rheumatoid factors measured in the patient's serum. This study reaffirms this observation and provides evidence that the reported differences are not artifacts of technique. The findings imply that rheumatoid factors of higher affinity for IgG than those of the serum are being released into the tissue fluids by lymphocytes and locally precipitated. Such rheumatoid factors may never reach the peripheral blood serum in detectable quantity or may do so only infrequently.

Animals↗
PubMedDate not supplied

Formation of DNA strand breaks by D-penicillamine and bucillamine in human lymphocytes.

DNA strand breakage by D-penicillamine and bucillamine, anti-rheumatic agents with thiol residues was evaluated in DNA unwinding assays. When incubating human peripheral blood lymphocytes with D-penicillamine or bucillamine in the presence of 8 microM CuSO4, numerous DNA strand breaks occurred and those depended on the production of hydrogen peroxide and were completely blocked in the presence of catalase. This phenomenon was reversible, and fragmented DNA was repaired in 8 to 24 h. Significant decreases in cellular NAD levels were observed at concentrations of D-penicillamine or bucillamine which could damage DNA. As extensive depletion of cellular NAD functionally inactivates lymphocytes, the formation of DNA strand breaks may have a role in the immunomodulating action of these anti-rheumatic drugs.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Inhibition of IgE antibody formation by plasmid DNA immunization is mediated by both CD4+ and CD8+ T cells.

BACKGROUND: We previously showed that immunization of mice with plasmid DNA (pDNA) encoding the Escherichia coli beta-galactosidase gene (pCMV-LacZ) induces a Th1 response, whereas beta-galactosidase (beta-gal) in saline or alum induces a Th2 response. Furthermore, the Th1 response dominates over the Th2 response and downregulates preexisiting IgE antibody formation. Here, we determined by passive transfer of CD4+ or CD8+ lymphocytes and by immunizing beta2-microglobulin knockout (beta2-M KO) mice whether CD4+ and/or CD8+ cells from pDNA-immunized mice suppress IgE antibody production. METHODS: BALB/c mice were injected with either CD4+ or CD8+ lymphocytes from naive beta-gal-in-alum or pCMV-LacZ-immunized mice, then immunized with beta-gal in alum, and the IgE antibody formation was determined. Second, C57BL/6 wild-type (WT) or beta2-M KO mice were immunized with beta-gal orpCMV-LacZ, and the IgE antibody production was assessed. RESULTS: Passive transfer of both CD4+ and CD8+ lymphocytes from pDNA-immunized mice suppressed the IgE antibody response by 90% compared to transfer of CD4+ T cells from naive or beta-galin-alum immunized mice. beta2-M KO mice produced 3 times more IgE than the WT control mice both in the primary and secondary response. CONCLUSION: Both CD4+ and CD8+ subsets of T cells from pDNA-immunized mice can suppress IgE antibody production by affecting the primary response and/or by propagating the Th1 memory response in a passive cell transfer system. Immunization with pDNA-encoding allergens may be an effective new form of immunotherapy for atopic diseases.

Animals↗
PubMedDate not supplied

Probing of the rheumatoid factor (RF) V gene repertoire in rheumatoid arthritis (RA) by hybridoma clones.

Twenty human monoclonal antibodies with rheumatoid factor (RF) specificity were produced from fusions using B lymphocytes derived from the synovial tissue of two patients with rheumatoid arthritis (RA) and one with the polyarticular form of juvenile rheumatoid arthritis (JRA) (1). All the 20 monoclonal antibodies were IgM. Fourteen of these were classical RFs with specificity restricted to IgG, and included 12 kappa and 2 lambda proteins. When the fine specificity for IgG Fc determinants were investigated most of them showed the Ga specificity. In addition, 5 lambda and 1 kappa monoclonal RF antibodies showed polyreactivity and also reacted with various other antigens than IgG (1). The 14 monoreactive RFs were further studied for the expression of RF-related cross-reactive idiotypes (CRI) and variable heavy (VH) and light chain (VL) subgroups. Only four of the twelve kappa RFs expressed the V kappa III subgroup. Three of them belong to the V kappa IIIb sub-subgroup and expressed the CRI 17.109. One of these 3 clones in addition expressed the VH I associated CRI G6. Five other monoreactive RFs expressed either or both of the VH III associated CRI B6 and D12 (2). Using staphylococcal protein A (SPA) binding as well as Northern blotting techniques (2), studies indicated that 10 out of the 12 RFs studied expressed the VH III regions and 2 expressed the VH I region. These data, both for the heavy and light chains, indicated a different V gene usage by the RF derived from RA patients than by the RF M-components derived from patients with mixed cryoglobulinemia and Waldenström's macroglobulinemia but without RA.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMedDate not supplied

Regulation of rheumatoid factor synthesis.

Rheumatoid arthritis is associated with high titers of IgM and IgG autoantibodies against IgG (rheumatoid factors, RF) and is prevalent in individuals with the HLA haplotypes Dw4, Dw14 and DR1. Our investigations have aimed to determine the molecular genetic basis for RF autoantibody synthesis in people, in an effort to understand eventually how RF production may become improperly regulated in rheumatoid patients. The results have defined several cross-reactive idiotypes on the heavy and light chains of RFs that are serologic markers for specific immunoglobulin variable region genes. These autoantibody associated genes are highly conserved in human populations and are preferentially rearranged and expressed during early B cell development, and in certain lymphoproliferative diseases. They may be associated with a B cell subpopulation that is important for the processing and presentation to T cells of protein antigens trapped in immune complexes. These RF-associated idiotypes are eventually lost during the T cell dependent antibody diversification that accompanies rheumatoid arthritis. The stimuli for the diversification have not been clearly established. However, the rheumatoid arthritis disease susceptibility determinant on the beta-1 chain of individuals with the HLA Dw4, Dw14 or DR1 haplotypes is reproduced by the gp110 protein of the Epstein-Barr virus, and is a potent stimulus for T cell proliferation. Moreover, anti-gp110 antibodies are abundant in rheumatoid arthritis patients. Thus, it is possible that their continual binding and processing of gp110-IgG immune complexes by RF precursor B cells in the joints and other extravascular sites may lead to the emergence of self-reactive T cells that can trigger anti-IgG autoantibody synthesis in the absence of an external antigen.

Arthritis, Rheumatoid↗