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D L Robbins

Publications and source records attributed to D L Robbins.

At least 37 records · Page 2Linked to original sources
PubMed1992

Characterization and epitope mapping of human monoclonal antibodies to PDC-E2, the immunodominant autoantigen of primary biliary cirrhosis.

Further to define the epitopes of PDC-E2, the major autoantigen in primary biliary cirrhosis (PBC), we have developed and characterized five human monoclonal antibodies. These antibodies were derived by fusing a regional hepatic lymph node from a patient with PBC with the mouse human heterohybrid cell line F3B6. Previous studies of epitope mapping of PDC-E2 have relied on whole sera and have suggested that the immunodominant epitope lies within the inner lipoyl domain of the molecule. However, selective absorption studies using whole sera and a series of overlapping recombinant peptides of PDC-E2 have suggested that the epitope may also include a large conformational component. Moreover, several laboratories have suggested that autoantibodies against the 2-oxo acids dehydrogenase autoantigens are cross-reactive. The five monoclonal antibodies generated included three IgG2a and two IgM antibodies and were studied for antigen specificity using recombinant PDC-E2, recombinant BCKD-E2, histone, dsDNA, IgG (Fc), collagen and a recombinant irrelevant liver specific control, the F alloantigen. The antibodies were also used to probe blots of human, bovine, mouse and rat mitochondria. Finally, fine specificity was studied by selective ELISA and absorption against overlapping expressing fragments of PDC-E2. All five monoclonals, but none of the other mitochondrial autoantigens were specific for PDC-E2. In fact, although affinity purified antibodies to PDC-E2 from patients with PBC cross-reacted with protein X, the human monoclonals did not, suggesting that protein X contains an epitope distinct from that found on PDC-E2. Additionally, all three IgG2 monoclonals recognized distinct epitopes within the inner lipoyl domain of PDC-E2.

Animals↗
PubMed1992

Characterization of monoclonal IgG antibodies produced by hybridomas derived from rheumatoid synovial cells.

IgM rheumatoid factors (RF) are the predominant autoantibody found in rheumatoid arthritis. They are polyclonal, fix complement, and are directed against epitopes in the Fc portion of IgG. One hypothesis regarding the induction and persistence of RF production in rheumatoid arthritis is that the Fc of IgG is somehow altered, rendering it antigenic. In this study, to better understand the derivation and pathogenicity of RF in rheumatoid arthritis, monoclonal IgG (mIgG) constitutively secreting hybridomas were established by fusing rheumatoid synovial mononuclear cells (RSC) from patients with a mouse/human heteromyeloma cell line, F3B6. To clarify the primary structure of IgG Fc constant regions produced locally by RSC, we amplified the cDNA corresponding to the CH2 and CH3 domains of an IgG1-, IgG2-, and an IgG3-producing hybridoma derived from RSC. The amplified DNA segments were cloned in M13 vectors and sequenced. Interestingly, very few differences in the nucleotide sequences were observed, and the deduced amino acid sequences were identical, except for the allotype, with those encoded by the human germline genes GEA and CL. Thus, the primary structure of the IgG1, IgG2, and IgG3 Fc regions produced by RSC were not altered when compared with those encoded by the unmutated human germline gene. These results suggest that factors other than altered IgG induce and sustain high avidity RF production in rheumatoid arthritis.

Amino Acid Sequence↗
PubMed1990

Serologic and molecular characterization of a human monoclonal rheumatoid factor derived from rheumatoid synovial cells.

Molecular characterization of rheumatoid factors (RF) in rheumatoid arthritis (RA) has been hampered because of their polyclonality. To overcome this problem, we generated monoclonal RF-secreting hybridomas from rheumatoid synovial cells. Among the RF-secreting hybridomas, HAF10 secreted an IgM-RF that was monospecific for human IgG. It bound well to IgG1 and IgG2, but not to IgG3 and IgG4. Sequence analysis of its heavy and light chains showed that it contained a VH1 heavy chain and a V lambda light chain that did not belong to any known lambda light chain subgroup, and therefore, probably represented a new lambda subgroup. These results indicated that both the heavy and light chains of a monoclonal IgM-RF from rheumatoid synovial cells were quite different from the reported variable region sequences of several monoclonal RF derived mainly from patients with mixed cryoglobulinemia. Further studies of additional monoclonal RF from RA patients are warranted to define precisely their genetic basis and to further our understanding of the immunopathology of RA.

Amino Acid Sequence↗
PubMed1989

Characterization of four homologous L chain variable region genes that are related to 6B6.6 idiotype positive human rheumatoid factor L chains.

A significant proportion of monoclonal IgM rheumatoid factors (RF) from patients with mixed cryoglobulinemia express a KIIIa L chain-associated cross-reactive idiotype, termed 6B6.6. Previously, we reported the isolation from a patient with a monoclonal RF of a Vk gene, termed Humkv328, whose deduced amino acid sequence differs by three and seven residues from the L chains of the 6B6.6-positive RF Les and Pom, respectively. To further delineate the genetic basis of the 6B6.6 cross-reactive idiotype, we isolated from the same patient another Vk gene, termed Humkv329, which differs from kv328 by only three bases over a stretch of 1331 nucleotides sequenced. However, kv329 has a stop codon at amino acid position 94, and is thus a pseudogene. Therefore, we screened a second genomic library from an unrelated individual and isolated two potential function Vk genes (i.e., Humkv328h2 and Humkv328h5) which are highly homologous to Humkv328. All three potential functional Vk genes differ from each other by one to six bases over a 1331-bp stretch and all encode the same Vk region amino acid sequence. Among the six bases by which Humkv328h5 differs from Humkv328, two are in the conserved pentadecanucleotide region, which is known to be important in the regulation of k L chain transcription. In the future it will be important to ascertain the potential association of polymorphisms in the conserved pentadecanucleotide region with RF associated autoimmune and lymphoproliferative diseases.

Amino Acid Sequence↗
PubMed1988

Determination of the affinity of monoclonal 19 S IgM rheumatoid factor for IgG by modified immunoassay (ELISA).

In rheumatoid arthritis (RA), the pathogenicity of IgM rheumatoid factor (RF), an autoantibody whose antigen is IgG, is still unclear although RF-IgG complexes appear to be important mediators of immune injury. The polyclonality of RF in RA makes it difficult to characterize certain qualitative properties such as specificity and affinity which may be very important in determining pathogenicity. Monoclonal IgM RF can be used to circumvent this problem. Monoclonal RF secreting cells can be produced via hybridizations with RA B lymphocytes fused with mouse or human myeloma cell lines. Another source of monoclonal RF is the sera of patients with Waldenström's macroglobulinemia (WM). One particular WM IgM RF (Kas) was chosen for our experiments to measure affinities and specificities to eight different monoclonal IgGs (three IgG1s, three IgG3s, one IgG2, and one IgG4). 19 S IgM RF, a pentavalent molecule, was mildly reduced with DTT to make 7 S univalent fragments (7 S IgM RF). 7 S IgM RF was incubated with each of the different IgGs at several different concentrations. These mixtures were allowed to come to equilibrium. An aliquot was then used to determine the amount of free 7 S IgM RF by ELISA. By plotting the reciprocal of the fraction of bound RF versus the reciprocal of the concentration of free antigen at equilibrium, different affinities were determined. The results of these determinations compare favorably with published IgM RF affinities determined by more traditional methods. This method can also be used with proteolytic digest fragments of IgG and short synthetic peptides of the IgG molecule to better locate the antigen binding site. The technique may also help us to determine whether there are select clones of RSC producing RF with different affinities that could complex to a particular type of IgG which, in vivo, could produce greater inflammatory tissue damage. Furthermore, this methodology should be useful in the study of other autoimmune diseases characterized by pathogenic autoantibodies of differing affinities.

Antibodies, Anti-Idiotypic↗
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

Differential reactivity of rheumatoid synovial cells and serum rheumatoid factors to human immunoglobulin G subclasses 1 and 3 and their CH3 domains in rheumatoid arthritis.

19S IgM rheumatoid factors (RF) are polyclonal autoantibodies that may play an important pathogenic role in sustaining inflammatory synovitis in rheumatoid arthritis (RA). RF in RA have reactivity for as-yet-uncharacterized antigenic determinants in IgG Fc. We hypothesized that qualitative differences might exist between some of these RF molecules, and that differences such as reactivity and affinity might characterize more pathogenic RF molecules. Previous observations in our laboratory indicate that RF produced by rheumatoid synovial cells (RSC) have greater reactivity with human IgG and IgG3 subclass, in contrast to serum RF, which has greater reactivity with rabbit IgG and human IgG1. These observations were made using a complement-dependent RF plaque-forming cell assay. The purpose of this study was to validate and extend those observations. Therefore, we examined the reactivity of RSC and serum RF with human and rabbit IgG and the reactivity and avidity of RSC-RF for IgG1 and IgG3 molecules and Fab, F(ab')2, and pFc' fragments thereof in a solid-phase enzyme immunoassay. In particular, we found: RSC-RF had at least twice as much reactivity with human IgG as with rabbit IgG; serum RF had approximately equal reactivity with human and rabbit IgG; RSC-RF had greater reactivity and avidity for IgG3 and IgG3 pFc' than for IgG1; and RSC-RF was nonreactive with Fab or F(ab')2 from either IgG1 or IgG3. These results suggest that the major antigenic determinant for RSC-RF resides in the CH3 domain of the IgG3 molecule. Precise characterization of this epitope may provide further insight into the etiology and pathogenesis of RA.

Arthritis, Rheumatoid↗
PubMed1987

Gout and hyperuricaemia in systemic lupus erythematosus.

Coexistent gout and systemic lupus erythematosus (SLE) have received increasing attention. An additional case is reported and published cases reviewed. Common clinical features of this group include nephritis, diuretic and corticosteroid therapy and a tendency to be older and more frequently male. Prevalence of hyperuricaemia (HU) was assessed in 38 patients with SLE. HU was found in 29% and was closely associated with renal involvement particularly proteinuria and diuretic therapy. The presentation of gout in SLE may be modified or suppressed by anti-inflammatory therapy and may be misinterpreted as SLE arthritis.

Adolescent↗
PubMed1986

Estimation of the relative avidity of 19S IgM rheumatoid factor secreted by rheumatoid synovial cells for human IgG subclasses.

19S IgM rheumatoid factors (RF) may play an important role in sustaining inflammation in rheumatoid arthritis (RA). As yet, no unique antigenic specificity for RF in RA has been identified. Because the synovium is central to the pathogenic changes in RA, RF produced therein might be pathogenically more important than serum RF. Therefore, we examined the reactivity and relative avidity of 19S IgM-RF in serum and rheumatoid synovial cells (RSC) from 20 patients with seropositive RA. Reactivities were determined by competitive inhibition of serum RF hemolytic activity and RSC RF-plaque-forming cells (PFC) by added soluble antigen, i.e., monomeric human IgG subclasses. Estimation of relative avidities of RSC RF for human IgG subclasses was done by calculation of fractional RF expression in the RSC RF-PFC assay following inhibition by IgG subclasses. RSC RF had greatest reactivity with IgG3 and IgG1, some reactivity with IgG2, and the least reactivity with IgG4. Serum RF reacted most with IgG1 and IgG2, reacted some with IgG4, but reacted poorly with IgG3. The antigenic determinants with which RSC RF reacted were common to many IgG3 molecules. The highest relative avidity of RSC RF was for IgG3. These observations indicate a selective deficiency of serum RF compared with RSC RF and suggest an important pathogenic role for these qualitatively different RSC RF molecules for in situ RF immune complex-mediated inflammation in RA synovial tissue.

Animals↗
PubMed1986

Tocainide suppression of immune-complex-mediated dermal inflammation: comparison with prostaglandin E1.

Local anesthetic agents have been shown to alter a variety of polymorphonuclear leukocyte (PMN) functions and may be useful as anti-inflammatory agents. We compared the anti-inflammatory effects of therapeutic doses of the recently released local anesthetic-antiarrythmic drug tocainide to pharmacologic doses of prostaglandin E1 (PGE1) on immune-complex-mediated dermal inflammation in female Sprague-Dawley rats. Intense dermal inflammation was produced using a classic reverse passive Arthus reaction, and the inhibition of PMN accumulation in the subdermis was quantitated in biopsy samples taken 2.5 hr after the reaction was initiated and the drug was given. Using a light microscope with a counting grid, biopsy sections were randomly sampled in a blinded fashion and an inflammation index equal to the ratio of PMNs to fibroblasts was determined for each animal. The mean inflammation index in 10 animals given 25 mg of tocainide (mean serum level = 14.6 micrograms/ml) was 9.3 +/- 1.2 (+/- SEM), which was significantly less than the index of 17.7 +/- 2.5 in 10 control animals (P less than 0.025). Similarly, the five animals that received either 500 or 250 micrograms of PGE1 had a significantly reduced index, with the effect of 250 micrograms PGE1 comparable to the effect of the tocainide. These findings suggest that therapeutic levels of tocainide reduce the accumulation of PMNs in immune-complex-mediated dermal inflammation; thus, local anesthetic agents may be useful in the treatment of certain inflammatory disorders.

Alprostadil↗
PubMed1986

The age-related decline in antibody response is transferred by old to young bone marrow transplantation.

The immune response declines with age. This decline correlates with thymic involution and involves primarily a loss in T-cell function, whereas humoral immunity is more variably affected. In the current experiments we have measured immunoglobulin synthesis in vitro after mitogen stimulation, and specific antibody response after vaccination. We found that the response to pokeweed mitogen by non-specific immunoglobulin production, and the response to vaccine was shown to be transferred to lethally irradiated young mice by old to young bone marrow transplantation. Both pokeweed mitogen and tetanus toxoid require T-cell help for optimal response, and, therefore, our observations are in accordance with the age-associated decline in T-cell immunity. The finding that young hosts transplanted with old bone marrow produce less antibody than young hosts transplanted with young bone marrow highlights the importance of the decline in cellular function with age.

Aging↗
PubMed1986

Autoantibody profiles in juvenile arthritis.

Serologic and correlational testing was performed in a series of 65 patients diagnosed as having juvenile arthritis (JA) and in 21 age matched controls to detect the presence of antinuclear antibodies (ANA), antibodies to ssDNA, IgM and IgG rheumatoid factor (RF), immune complexes (IC) and antibodies to bovine type I and human type II collagen. ANA were found in 51% of the JA patients; the highest incidence (75%) was noted in the pauciarticular onset disease group. Low levels of anti-ssDNA antibodies were detected in 22% of the patients, all of whom had active disease. IgM RF was detected in 35% of the JA patients but only 6% of patients had IgG RF. Similarly, about one fourth of the JA patients had IC detected by the Clq assay. Antibodies to bovine type I and human type II collagen were noted in about 12% of the JA patients.

Adolescent↗
PubMed1986

Complement activation by 19S IgM rheumatoid factor: relationship to disease activity in rheumatoid arthritis.

19S IgM rheumatoid factor (RF) in rheumatoid arthritis (RA) are polyclonal autoantibodies directed against the Fc piece of IgG. Rheumatoid patients with RF tend to have aggressive synovitis, nodules, and extraarticular manifestations. Although RF titer does not correlate with disease activity, RF activates complement (C) by the classical pathway. Thus, we postulated that selective stimulation of cell clones producing efficient C activating RF molecules might be associated with disease flares, independent of changes in serum RF concentration. To address the question, 42 patients with RA were evaluated prospectively. Serum RF concentration was measured by radioimmunoassay (RIA) and C activating activity by hemolytic assay. We then calculated the mean hemolysis (MH) of sensitized sheep erythrocytes (SRC) produced/ml of RF serum (MH/ml) and MH/microgram of RF as an expression of RF C activating properties (CAP). The following observations were made: RF CAP varied among the patients studied; RF CAP varied over time in individual patients; RF CAP differences varied in both groups independently from RF concentration; RF CAP correlated with both systemic and articular disease activity; and total RF concentration correlated with articular findings and nodules but less well with systemic disease activity.

Adult↗
PubMed1986

Relationship of serum IgG rheumatoid factor to IgM rheumatoid factor and disease activity in rheumatoid arthritis.

Rheumatoid factors (RF) constitute the major autoantibodies in rheumatoid arthritis (RA). RF are directed against IgG Fc, are polyclonal, and are predominantly of the IgG and IgM classes. RF may participate in both synovial and extraarticular inflammation in RA, although the precise roles of serum IgG and IgM RF are unclear. The purpose of our study was to correlate serum IgG RF with serum IgM RF levels measured by radioimmunoassay and with clinical disease activity in 42 prospectively evaluated seropositive RA patients. IgM RF correlated with IgG RF levels and articular disease activity. IgG RF correlated with IgM RF but not with articular disease activity when adjusted for IgM RF.

Arthritis, Rheumatoid↗
PubMed1985

Giant cell arteritis associated with mononeuritis multiplex and complement-activating 19S IgM rheumatoid factor.

Giant cell arteritis is a necrotizing granulomatous arteritis of large arteries, especially the aorta and its branches. Mononeuritis multiplex is a peripheral sensorimotor neuropathy usually producing foot or wrist drop, commonly associated with necrotizing arteritis of small and medium-sized arteries. Rheumatoid vasculitis is an example of the latter type of arteritis associated with high-titer 19S IgM rheumatoid factor typically occurring in patients with long-standing erosive rheumatoid arthritis. This report describes a 71-year-old man with biopsy-proved giant cell arteritis, mononeuritis (foot drop) multiplex, and high-titer complement-activating rheumatoid factor without rheumatoid arthritis. Possible pathogenic relationships are discussed.

Aged↗