Oligonucleotide linked to human gammaglobulin specifically diminishes anti-DNA antibody formation in cultured lymphoid cells from patients with systemic lupus erythematosus

SLE: translating lessons from model systems to human disease

Systemic lupus erythematosus (SLE, lupus) results from immune-mediated damage to multiple organs. Its pathogenesis should be viewed as a series of steps, beginning with impaired immune regulation that permits self-reactive T-B-cell activation, which results in the production of autoantibodies. Activated T and B cells then infiltrate tissues, which along with autoantibody and immune complex deposition, triggering local events that ultimately cause organ damage. Although improved understanding of early autoimmune events might open up avenues for disease prevention, future investigations must focus on the mechanisms of end-organ damage in model systems and how to translate this knowledge into human disease. Understanding the mechanisms of each pathogenetic step would provide a rational basis for the development of disease stage-specific diagnostic markers and treatments.

Induction of tolerance by administration of hapten-immunoglobulin conjugates is associated with decreased IL-2 and IL-4 production

Intravenous administration of trinitrophenyl-modified isologous immunoglobulin-induced nonresponsiveness to subsequent epicutaneous painting of sensitizing doses of trinitrochlorobenzene. Isologous immunoglobulin with various degrees of trinitrophenyl substitution (11.2, 14.3, 27 and 47.3) prevented sensitization. The suppression of contact hypersensitivity was dependent on the dose of tolerogen and was hapten specific. Tolerance was inducible in mice of the strains CBA (H-2k), C57BL/6 (H-2b), and DBA/2 (H-2d) but not in Balb/C (H-2d) mice, suggesting that this trait maps outside the murine major histocompatibility complex. Tolerance induced by trinitrophenyl-modified immunoglobulin was associated with decreased hapten-induced proliferation of draining lymph-node cells. Unlike in other models of tolerance in which a decreased interleukin-2 to interleukin-4 ratio can be observed, administration of tolerizing trinitrophenylated immunoglobulin was associated with deficient hapten-induced release of both interleukin-2 and interleukin-4.

Conjugates or dsDNA linked to human gammaglobulin inhibit anti-dsDNA antibodies in vitro

Previous studies have shown that both nucleosides and oligonucleotides linked to isologous gammaglobulin suppress anti-nucleic acid antibody production both in vivo and in vitro. The aim of this study was to determine whether one can make a DNA-human gammaglobulin (HGG) conjugate which can inhibit anti-double stranded DNA (dsDNA) antibodies obtained from a heterogeneous population of systemic lupus erythematosus (SLE) sera. To do so, we constructed conjugates of sonicated dsDNA fragments of 100-400 base pairs covalently linked to HGG with varying degrees of substitution of DNA:HGG. An ELISA inhibition assay was used to determine which conjugate best inhibits the binding of anti-dsDNA antibodies. Conjugate 2, prepared with monomeric HGG (150 kD) with a high degree of substitution (3.72 DNA:HGG) inhibited the binding of anti-dsDNA antibodies from 27 of 31 SLE sera. In addition, this conjugate inhibited the spontaneous formation of anti-dsDNA in vitro by cultured lymphoid cells from selected SLE patients. Together, this data suggests that a 'generic' tolerogen may provide an antigen specific therapy for SLE.

DNA-binding antibodies and parasitic diseases

DNA-binding antibodies are produced during the course of many parasitic infections, including malaria, leprosy and schistosomiasis. These antibodies are also present in certain autoimmune diseases, such as systemic lupus erythematosus, and much information is available about their properties and contribution to related disease processes Here, Anne Wozencraft and Norman Staines consider how DNA-binding antibodies might arise during parasitic infection and discuss how an increased knowledge of their properties and functions could lead to a greater understanding of mechanisms of immuno-pathology in these diseases.

A novel technique to link either proteins or peptides to gammaglobulin to construct tolerogens

In order to extend the concept of constructing tolerogens (i.e., compounds which induce immunologic tolerance), we developed a novel method to covalently link either protein or peptide to isologous gammaglobulin. We used disuccinimidyl suberate (DSS) for preparing protein conjugates in solution in a novel use of this reagent. We tested the efficacy of this method in two different experimental models: in the first, we found that administration of pigeon cytochrome C conjugated to mouse IgG in vivo induces T cell unresponsiveness in vitro. In the second, we induced unresponsiveness to factor VIII light chain both in newborn and, more importantly, in adult mice already immune to factor VIII. We hope that this simple method will provide a powerful tool to construct tolerogens useful in the specific treatment of either allergic or autoimmune diseases.

Immunologic tolerance to DNA in B cell lines from both normal and autoimmune mice

We examine whether B cell lines enriched for DNA specificity from either autoimmune (BWF1) or normal mice (Balb/c) can be rendered unresponsive to autoantigen in terms of the specific suppression of direct antibody-forming cells to DNA. These B cell lines were both Lyt-1 positive and negative. Preincubation with oligonucleotide, covalently linked to mouse gamma-globulin, specifically suppressed the antigen-driven response elicited by DNA horse red blood cells in B cell lines from both strains of mice. There is a 5-fold difference in susceptibility to DNA-specific tolerance induction between B cell lines of BWF1 and Balb/c mice. Thus, B cells from autoimmune mice do not appear to have an inherent absolute defect in being rendered tolerant to autoantigen, but are relatively less susceptible to DNA-specific tolerance than nonautoimmune cell lines.