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Biomedical subjects

D A Carson

Publications and source records attributed to D A Carson.

At least 199 records · Page 11Linked to original sources
PubMed1988

A 16/6 idiotype-positive anti-DNA antibody is encoded by a conserved VH gene with no somatic mutation.

Recently, the heavy chain of 16/6 idiotype-positive human anti-DNA antibodies was found to be similar, but not identical, to the VH26 gene. We resequenced the VH26 gene and found that its coding sequence is actually identical to the complementary DNA sequence of the anti-DNA antibodies previously described. Together with the previous data, our findings demonstrate that some human autoantibodies are encoded directly by immunoglobulin V region genes, and that these V region genes are remarkably conserved in populations.

Antibodies, Antinuclear↗
PubMed1988

Programmed cell death and adenine deoxynucleotide metabolism in human lymphocytes.

Agents that cause the accumulation of DNA strand breaks are directly cytotoxic to non-dividing normal human peripheral blood lymphocytes, and to chronic lymphocytic leukemia (CLL) cells. Activation of poly(ADP-ribose) polymerase (ADPRP), and the resultant consumption of NAD, play an essential role in mediating the toxicity of these agents. Human peripheral blood lymphocytes contain a substantial number of alkali-sensitive DNA sites, reflecting ongoing DNA strand breakage and repair. However, resting lymphocytes have a limited capacity to synthesize NAD. Pulse-chase experiments indicate that approximately 75% of their NAD turnover is due to ADPRP activity. Exposure of the cells in vitro to deoxyadenosine, or to 2-chlorodeoxyadenosine (CdA, an adenosine deaminase resistant deoxyadenosine congener), caused an increase in DNA strand breaks, rapid NAD consumption, ATP depletion and cell death. Supplementation of the medium with inhibitors of poly(ADP-ribose) polymerase blocks the fall in cellular NAD and ATP, and protects the lymphocytes from the toxicity of DNA damaging agents. Slowly dividing malignant lymphocytes from patients with CLL are also susceptible to lethal NAD depletion following DNA damage. 2-chlorodeoxyadenosine (CdA) induced massive DNA strand break formation in CLL cells in vitro and a fall in NAD and ATP pools. In an initial clinical trial, several CLL patients, and two patients with hairy cell leukemia, have responded to treatment with CdA, with minimal toxicity. Thus, the suicidal activation of ADPRP in response to DNA damage has been rationally exploited in the treatment of chronic lymphoid malignancies.

Cell Survival↗
PubMed1988

Immunogenic and antigenic epitopes of immunoglobulins. XXIII. Idiotypy and molecular specificity of human rheumatoid factors: analysis of cross-reactive idiotype of rheumatoid factor paraproteins from the Wa idiotype group in relation to their IgG subclass specificity.

The expression of idiotypic and variable region-associated isotypic determinants on a panel of human monoclonal rheumatoid factors (RF) was studied by means of murine hybridoma antibodies produced to two IgM-RF paraproteins. Fourteen RF paraproteins from patients with cryoglobulinaemia and one (RF-AN) from an Epstein-Barr virus (EBV)-established B-cell line from a patient with rheumatoid arthritis (RA) were studied. Nine RF paraproteins expressed a VkIIIb light chain sub-subgroup-associated cross-reactive idiotype and seven of these nine also expressed a heavy chain-associated cross-reactive idiotype. The reactivity of the monoclonal RF with human IgG subclass paraproteins revealed four patterns of molecular specificities: (1) RF reactive with an epitope common to all IgG subclasses; (2) RF reactive with an epitope expressed on IgG1, 2, 4 and G3m(s,t) which has histidine at 435, but not G3m(b) or G3m(g) which have arginine at 435; (3) RF reactive with an epitope expressed on IgG1, 2, and 4, but not IgG3 irrespective of allotypic markers; (4) RF reactive with epitopes expressed on some, but not all paraproteins within the subclasses. Four of five RF paraproteins that expressed both the heavy and light chain-associated idiotopes showed a similar pattern of reactivity with IgG subclass proteins.

Cross Reactions↗
PubMed1988

Idiotypic and subgroup analysis of human monoclonal rheumatoid factors. Implications for structural and genetic basis of autoantibodies in humans.

Rheumatoid factors (RFs) in humans have been studied intensively because of their association with autoimmune and lymphoproliferative diseases. Many human IgM-RFs express cross-reactive idiotypes (CRIs) and have homologous light chains, some of which are encoded by a single V kappa gene, termed V kappa 325. However, although antibody activity generally requires the interaction between heavy and light chain variable regions, much less is known about structural relationships among RF heavy chains. To delineate further the structural and genetic basis of RF autoantibody synthesis, we generated "sequence-dependent" reagents specific for the human heavy and kappa light chain subgroups, and used them to analyze a panel of 27 monoclonal RFs. In addition, these proteins were tested for the expression of a heavy chain-associated CRI (G6), and a light chain-associated CRI (17.109). The results showed that most 17.109-reactive RFs contain heavy chains of the VHI subgroup, which bear the G6 idiotypic marker. However, among the 14 17.109-reactive RFs, two have heavy chains of the VHII subgroup, and another two contain heavy chains of the VHIII subgroup. Previously, we have shown that 17.109 is a phenotypic marker of the human V kappa 325 gene. Accordingly, these results demonstrate that the same human V kappa gene can combine with several VH genes from different VH gene subgroups to generate RF activity.

Amino Acid Sequence↗
PubMed1988

Idiotypic characteristics of rheumatoid factors.

We have used monoclonal anti-idiotypic antibodies and "sequence-dependent" heterologous anti-peptide antibodies of predefined specificities against either the complementarity determining or framework regions of the human immunoglobulin molecules to delineate the structural and genetic basis of human IgM rheumatoid factor (RF) paraprotein formation. Human IgM RF paraproteins were found to be most commonly reactive with anti-kappa III subgroup anti-sera (88%). These RFs could be subdivided into two major light chain cross reactive idiotype (CRI) groups with the monoclonal antibodies 17.109 and 6B6.6. The two CRI positive light chains are likely encoded by two distinct V kappa germline genes, designated respectively Humkv325 (VkRF) and Humkv328. These CRIs are also associated with specificities other than RFs. Heavy chain analysis of RFs revealed that the product of the Humkv325 gene frequently assemble with heavy chains of the VHI subgroup, but will assemble with the heavy chains of other subgroups less frequently. The VHI heavy chains RFs were found to carry frequently the G6 CRI marker.

Antibodies, Monoclonal↗
PubMed1988

2-Chlorodeoxyadenosine: an effective new agent for the treatment of chronic lymphocytic leukemia.

2-Chlorodeoxyadenosine, a new lymphocyte-selective, anti-neoplastic drug was administered to 18 patients with advanced chronic lymphocytic leukemia of B-cell origin. All patients were resistant to conventional treatment. A total of 44 courses of 2-chlorodeoxyadenosine were completed with minimal toxicity. An overall response rate of 55% was achieved with four of 18 patients demonstrating partial response and six of 18 patients experiencing clinical improvement. Only minor bone marrow suppression occurred during administration of the drug, indicating a high degree of lymphocyte selectivity. Reduction of lymphocyte infiltration in bone marrow occurred in treated patients including one patient who experienced normalization of the bone marrow. Three of four patients with concurrent autoimmune hemolytic anemia experienced resolution of hemolysis, as indicated by elimination of transfusion requirement, fall in reticulocyte count, elevation of hemoglobin, and ability to taper prednisone without recurrence of hemolysis. Duration of responses ranged from 2 to 15 months without maintenance therapy.

Adult↗
PubMed1988

Autoantibody-associated cross-reactive idiotypes expressed at high frequency in chronic lymphocytic leukemia relative to B-cell lymphomas of follicular center cell origin.

Using murine monoclonal antibodies (MoAbs) specific for immunoglobulin (Ig) cross-reactive idiotypes (CRI), we performed immunohistochemical analyses on frozen tissue sections and cytocentrifuge preparations of Ig-expressing malignant cells from patients with chronic lymphocytic leukemia (CLL) and B-cell non-Hodgkin's lymphomas (NHL) of follicular center cell origin. Twenty percent (4/20) of the Ig kappa light chain-expressing CLL cells reacted with 17.109, a MoAb against a major CRI on human IgM autoantibodies that is encoded by a conserved Ig variable-region gene (V gene) of the V kappa IIIb sub-subgroup. Another MoAb specific for V kappa IIIb framework determinant(s) reacted exclusively with all the 17.109-reactive CLL cells. Only one of 20 kappa light-chain-expressing CLL cells reacted with 6B6.6, a monoclonal antibody specific for a CRI commonly found on rheumatoid factor (RF) paraproteins with light-chain variable regions of the V kappa IIIa sub-subgroup. Finally, greater than 20% (8/34) of all CLL reacted with G6, a MoAb specific for an Ig heavy chain-associated CRI present on several RF paraproteins. In contrast, these CRIs were expressed at significantly lower frequencies in NHL of follicular center cell origin. Only one of 30 NHL expressing kappa light chains reacted with the 17.109 MoAb. Also, in contrast to the concordance between the 17.109-CRI and V kappa IIIb framework determinant(s) in CLL, two lymphomas in addition to the 17.109-reactive lymphoma were recognized by the anti-V kappa IIIb framework MoAb. None of the NHL reacted with either the 6B6.6 or the G6 MoAbs. These results are the first to demonstrate that CLL and NHL differ with respect to the expression of autoantibody-associated CRIs. The data support the notion that NHL of follicular center cell origin differs from CLL in its utilization and/or somatic mutation of Ig variable-region genes. The physiological and immunotherapeutic implications of these findings are discussed.

Autoantibodies↗
PubMed1987

Isolation and characterization of a light chain variable region gene for human rheumatoid factors.

Previously, we isolated a Vk gene (Humkv325) from a human placenta that encodes RF light chains bearing the PSL2 and PSL3 CRI markers. Here we report the isolation and characterization of a second human Vk gene (Humkv328) that can be used for RF synthesis. This Vk gene probably encodes at least two 6B6.6 CRI+ RF light chains (Les and Pom) from unrelated subjects, and thus may be related to the light chain-associated 6B6.6 CRI.

Amino Acid Sequence↗
PubMed1987

Failure of dideoxynucleosides to inhibit human immunodeficiency virus replication in cultured human macrophages.

Primary human monocyte-derived macrophages (MDM) were shown to have diminished deoxynucleoside kinase activities compared to T lymphoblasts, and a reduced ability to phosphorylate dideoxynucleosides with anti-human immunodeficiency virus (HIV) activity. These drugs, azidothymidine (AZT), dideoxycytidine (ddC), and dideoxyadenosine (ddA), which are potent anti-HIV agents in CD4 lymphocytes, did not inhibit HIV replication in MDM, even at concentrations of 100 microM. This drug concentration of AZT is approximately 100-fold higher than the levels attained in the serum of treated patients and the levels required to inhibit HIV replication in lymphocytes. These observations may explain the failure of AZT therapy to clear viremia, consistent with the presence of a drug-resistant reservoir of infected cells in vivo. New therapeutic approaches to inhibit the replication of HIV in MDM may be needed.

Adenosine Kinase↗
PubMed1987

Isolation and characterization of human VkIII germ-line genes. Implications for the molecular basis of human VkIII light chain diversity.

To understand the relative importance of germ-line genes in the generation of the functional human antibody repertoire, it is first necessary to define the number of variable region genes and to determine their fine structure. We have focused on the human VkIII variable region gene family because of its association with autoantibodies. A human genomic library was screened with a VkIII cDNA probe and subsequently with a VkIII germ-line gene probe. Seven different VkIII clones were isolated and characterized by restriction mapping and sequence analyses. Three clones have identical restriction enzyme sites over a 12-kilobase (kb) region, contain identical sequences over an 895-base pair (bp) region, and thus are likely to be different isolates of the same human VkIII gene. Another two clones have identical restriction enzyme sites over a 5-kb region, are identical over a stretch of 905 bp sequenced, and likely represent independent isolates of another human VkIII gene. The remaining two VkIII clones consist of two additional VkIII genes which are homologous to each other, but are quite different from the first two VkIII genes. Thus, four new human VkIII genes were defined. Together with four other VkIII genes previously isolated by other investigators, a total of eight human VkIII germ-like genes have now been described. A comparison of the deduced amino acid sequences of these genes with the reported amino acid sequences of all human VkIII light chains suggests that at least one additional VkIII gene exists in the germ line. Among the eight identified human germ-line VkIII genes, three are pseudogenes. Of the remaining five potential functional genes, one gene seems to encode a majority of the VkIII light chains which have been sequenced. Possible explanations for this phenomenon are discussed.

Amino Acid Sequence↗
PubMed1987

Structural and functional characteristics of the CD3 (T3) molecular complex on human thymocytes.

The CD3 (T3) molecular complex is noncovalently associated with the antigen receptor molecule on T cells. The mitogenic properties of anti-CD3 antibodies have suggested that this complex may be the transducer of the antigenic signal to the intracellular environment. In the present investigation, we studied some of the structural and functional characteristics of the CD3 complex on human thymocytes. In 11 specimens tested, we found that anti-CD3 antibodies react with 50 to 76% of the thymocytes. Two-color immunofluorescence analysis revealed that the majority (greater than 50%) of thymocytes express both CD3 and CD1 on their surfaces. The latter is a marker of immature thymocytes. However, a distinct subpopulation comprising 13 to 19% of the total cells displays only CD3, while an approximately equal percentage of cells expresses only CD1. The mitogenic potential of anti-CD3 antibodies on peripheral T cells is dependent on the presence of monocytes. Anti-CD3 antibodies by themselves cannot activate thymocytes, indicating that functionally active monocytes are absent from the thymocyte population. Even the addition of peripheral monocytes does not allow a response of thymocytes to anti-CD3 antibodies. However, when the anti-CD3 antibody 64.1 is added in the presence of exogenous rIL 2, a strong antibody and lymphokine dose-dependent response ensues. Only CD1- CD3+ thymocytes are stimulated by the addition of antibody and IL 2. The mere expression of CD3 on the CD1+ CD3+ subpopulation of thymocytes apparently is not sufficient to render the cells responsive to the signals of anti-CD3 and IL 2.

Antibodies, Monoclonal↗
PubMed1987

Adenosine deaminase activity in recipients of bone marrow from immunodeficient mice homozygous for the wasted mutation.

Mice homozygous for the mutation wasted (wst/wst) have been postulated to be a model for the form of human severe combined immunodeficiency disease (SCID) that is secondary to a genetic deficiency of adenosine deaminase (ADA). To test this hypothesis more critically, we transplanted marrow from wst/wst and littermate control mice into lethally irradiated normal recipients. The Vmax and Km values for ADA in recipient's hematologic and non-hematologic tissues did not differ significantly. These results indicate that the wasted mouse is not a model for ADA deficiency and SCID.

Adenosine Deaminase↗
PubMed1987

Autoantibodies in infectious mononucleosis have specificity for the glycine-alanine repeating region of the Epstein-Barr virus nuclear antigen.

Viruses have been postulated to be involved in the induction of autoantibodies by: autoimmunization with tissue proteins released by virally induced tissue damage; immunization with virally encoded antigens bearing molecular similarities to normal tissue proteins; or nonspecific (polyclonal) B cell stimulation by the infection. Infectious mononucleosis (IM) is an experiment of nature that provides the opportunity for examining these possibilities. We show here that IgM antibodies produced in this disease react with at least nine normal tissue proteins, in addition to the virally encoded Epstein-Barr nuclear antigen (EBNA-1). The antibodies are generated to configurations in the glycine-alanine repeat region of EBNA-1 and are crossreactive with the normal tissue proteins through similar configurations, as demonstrated by the effectiveness of a synthetic glycine-alanine peptide in inhibiting the reactions. The antibodies are absent in preillness sera and gradually disappear over a period of months after illness, being replaced by IgG anti-EBNA-1 antibodies that do not crossreact with the normal tissue proteins but that are still inhibited by the glycine-alanine peptide. These findings are most easily explained by either a molecular mimicry model of IgM autoantibody production or by the polyclonal activation of a germline gene for a crossreactive antibody. It also indicates a selection of highly specific, non-crossreactive anti-EBNA-1 antibodies during IgM to IgG isotype switching.

Alanine↗