Debra Jeske Zack

Bio: Debra Jeske Zack is an academic researcher from Veterans Health Administration. The author has contributed to research in topics: Antibody & Autoantibody. The author has an hindex of 8, co-authored 9 publications receiving 456 citations.

Mechanisms of cellular penetration and nuclear localization of an anti-double strand DNA autoantibody.

Abstract: An anti-dsDNA Ab, mAb 3E10, was identified that bound membranes of fixed human renal tubular cells, penetrated live murine renal tubular cells in vivo, and localized in the cell nucleus. mAb 3E10 binds both dsDNA and an extracellular matrix protein, HP8/HEVIN, expressed in high endothelial venules. Previous studies showed both shared and distinct binding determinants of mAb 3E10 VH for DNA and HP8/HEVIN. To independently assess the requirement of DNA and HP8/HEVIN in cellular penetration, site-directed mutants of mAb 3E10 VH and V kappa were studied for penetrating kidney cell lines. The results showed that residues required for binding DNA, but not HP8/HEVIN, were necessary for Ab penetration, indicating that cellular penetration required the presence of DNA or binding of Ab to a membrane determinant precisely resembling DNA. Ab Fab penetrated cells, indicating that neither the Fc nor multivalent Ab binding is necessary for cellular penetration. Ab synthesized in the cytoplasm as a result of deleting heavy and light chain signal peptides was not translocated to the nucleus, indicating a mechanism distinct from the usual protein nuclear localization signals and suggesting the need for a membrane-mediated pathway or for post-translational modification of the Ab.

Genetic Determinants of Autoimmune Disease and Coronary Vasculitis in the MRL-lpr/lpr Mouse Model of Systemic Lupus Erythematosus

Abstract: MRL-lpr/lpr (MRL/lpr) mice are a model of human autoimmune disease. They exhibit a number of characteristics of systemic lupus erythematosus, including anti-DNA Abs, anti-cardiolipin Abs, immune complex-mediated vasculitis, lymphadenopathy, and severe glomerulonephritis. Although the autoimmune disorder is mediated primarily by mutation of the Fas gene (lpr), which interferes with lymphocyte apoptosis, MRL/lpr mice also have other predisposing genetic factors. In an effort to identify these additional factors, we have applied quantitative trait locus (QTL) mapping using an intercross between MRL/lpr mice and the nonautoimmune inbred strain BALB/cJ. A complete linkage map spanning the entire genome was constructed for 189 intercross progeny, and genetic loci contributing to features of the autoimmunity were identified using statistical analytic procedures. As expected, the primary genetic determinant of autoimmune disease in this cross was the Fas gene on mouse chromosome 19, exhibiting a lod score of 60. In addition, two novel loci, one on chromosome 2 (lod score, 4.3) and one on chromosome 11 (lod score, 3.1), were found to contribute to levels of anti-DNA Abs. Interestingly, the chromosome 19 and chromosome 11 QTLs, but not the chromosome 2 QTL, also exhibited associations with anti-cardiolipin Abs (lod scores, 38.4 and 2.6). We further examined the effects of these QTLs on the development of coronary vasculitis in the F2 mice. Our results indicate that the QTLs on chromosomes 11 and 19 also control the development of vasculitis, demonstrating common genetic determinants of autoantibody levels and vasculitis.

DNA mimics a self-protein that may be a target for some anti-DNA antibodies in systemic lupus erythematosus.

Abstract: Recent studies suggest that some anti-DNA Abs in systemic lupus erythematosus may actually be Abs to specific proteins and that binding to dsDNA is a nonspecific cross-reactive event To identify such proteins that bind to anti-DNA Abs, a cDNA expression library from human placenta was screened with mAb 3E10, a pathogenic anti-dsDNA Ab MAb 3E10 was shown to bind to a 44-amino-acid fragment of HP8, a newly identified protein with amino acid sequence homology to the family of SPARC extracellular matrix proteins To determine if Ab binding to both dsDNA and HP8 protein occurs through a common binding site, and therefore represents molecular mimicry, the Ab binding domains for protein and DNA were mapped Chain recombinations between mAb 3E10 and a non-anti-DNA mAb showed that both the heavy and the light chains of mAb 3E10 were essential for anti-dsDNA and anti-HP8 reactivity Mutagenesis experiments demonstrated that dsDNA and HP8 shared several critical binding residues located in all three complementarity-determining regions of mAb 3E10 VH Moreover, Abs to HP8 were demonstrated in the sera of a subset of lupus patients These results indicate that DNA mimics the HP8 protein in binding a lupus Ab, and that this protein may be a target for a subpopulation of anti-dsDNA Abs in systemic lupus erythematosus

Localization of an Fc-binding reactivity to the constant region of human IgG4. Implications for the pathogenesis of rheumatoid arthritis

Abstract: The majority of plasma cells in rheumatoid arthritis (RA) synovium produce rheumatoid factors (RF). IgG RF predominate in the immune complexes found in RA synovial fluid and have been implicated in the pathogenesis of RA. IgG4 RF are a major component of IgG RF produced in serum and synovium of RA patients, even though this subclass comprises only 4% of the serum IgG. We produced an IgG4 mAb, hRF-1, with RF reactivity from the synovial tissue of a patient with RA. mAb hRF-1 had binding specificity for mammalian IgG similar to Staphylococcus aureus protein A, which is characteristic of RF from patients with RA. To determine the molecular basis of this particular RF reactivity, the heavy and light chain genes of mAb hRF-1 were amplified by PCR, cloned, and ligated into the pSG5 plasmid for expression in COS-7 cells. Chain recombination experiments localized the Fc-binding reactivity to the hRF-1 heavy chain. Using a series of chimeric Ab sequences, the Fc-binding reactivity was mapped to the constant region of IgG4 rather than the variable region involved in classic RF reactivity. Multiple domains, including Hinge, CH2, and CH3 of the IgG4 constant region were required for Fc binding. Our studies demonstrate an example of RF-like Fc-binding reactivity that is conferred by the gamma-4 constant region rather than the classic Ag binding site and suggest that increased production of IgG4 may contribute to the pathogenesis of RA.

Genetic Dissection of Complex Traits

Abstract: Medical genetics was revolutionized during the 1980s by the application of genetic mapping to locate the genes responsible for simple Mendelian diseases. Most diseases and traits, however, do not follow simple inheritance patterns. Geneticists have thus begun taking up the even greater challenge of the genetic dissection of complex traits. Four major approaches have been developed: linkage analysis, allele-sharing methods, association studies, and polygenic analysis of experimental crosses. This article synthesizes the current state of the genetic dissection of complex traits—describing the methods, limitations, and recent applications to biological problems.

Paraneoplastic Syndromes Involving the Nervous System

Abstract: Paraneoplastic neurologic syndromes are incited by a tumor outside the nervous system that produces a characteristic antigen of the nervous system. An immune response against the ectopic tumor antigen not only damages nerve tissue but also inhibits growth of the tumor.

Immunoglobulin G4: an odd antibody

Abstract: Despite its well-known association with IgE-mediated allergy, IgG4 antibodies still have several poorly understood characteristics. IgG4 is a very dynamic antibody: the antibody is involved in a continuous process of half-molecules (i.e. a heavy and attached light-chain) exchange. This process, also referred to as 'Fab-arm exchange', results usually in asymmetric antibodies with two different antigen-combining sites. While these antibodies are hetero- bivalent, they will behave as monovalent antibodies in most situations. Another aspect of IgG4, still poorly understood, is its tendency to mimic IgG rheumatoid factor (RF) activity by interacting with IgG on a solid support. In contrast to conventional RF, which binds via its variable domains, the activity of IgG4 is located in its constant domains. This is potentially a source of false positives in IgG4 antibody assay results. Because regulation of IgG4 production is dependent on help by T-helper type 2 (Th2) cells, the IgG4 response is largely restricted to non-microbial antigens. This Th2-dependency associates the IgG4 and IgE responses. Another typical feature in the immune regulation of IgG4 is its tendency to appear only after prolonged immunization. In the context of IgE-mediated allergy, the appearance of IgG4 antibodies is usually associated with a decrease in symptoms. This is likely to be due, at least in part, to an allergen-blocking effect at the mast cell level and/or at the level of the antigen-presenting cell (preventing IgE-facilitated activation of T cells). In addition, the favourable association reflects the enhanced production of IL-10 and other anti-inflammatory cytokines, which drive the production of IgG4. While in general, IgG4 is being associated with non-activating characteristics, in some situations IgG4 antibodies have an association with pathology. Two striking examples are pemphigoid diseases and sclerosing diseases such as autoimmune pancreatitis. The mechanistic basis for the association of IgG4 with these diseases is still enigmatic. However, the association with sclerosing diseases may reflect an excessive production of anti-inflammatory cytokines triggering an overwhelming expansion of IgG4-producing plasma cells. The bottom line for allergy diagnosis: IgG4 by itself is unlikely to be a cause of allergic symptoms. In general, the presence of allergen-specific IgG4 indicates that anti-inflammatory, tolerance-inducing mechanisms have been activated. The existence of the IgG4 subclass, its up-regulation by anti-inflammatory factors and its own anti-inflammatory characteristics may help the immune system to dampen inappropriate inflammatory reactions.

Anti-double-stranded DNA antibodies and immunostimulatory plasmid DNA in combination mimic the endogenous IFN-alpha inducer in systemic lupus erythematosus.

Abstract: Anti-double-stranded DNA antibodies and immunostimulatory plasmid DNA in combination mimic the endogenous IFN-alpha inducer in systemic lupus erythematosus