Southwestern Internal Medicine Conference: high-dose intravenous gamma globulin therapy: how does it work?

In the past, IgG replacement has been used primarily to treat patients with hypoglobulinemia or agammaglobulinemia. With the availability of preparations of IgG suitable for intravenous use (IVIG), much higher doses may now be given safely. Surprisingly, administration of very high doses of IVIG in several immunologically related diseases have produced improvement not achieved by other means of therapy. The mechanisms by which IVIG causes these diseases to improve vary with the immunopathogenesis of each disease. Provision of antibodies otherwise unavailable to a given patient, IgG-Fc-receptor blockade, modification of complement activation and modulation of the immune response by anti-idiotypic antibodies are discussed as mechanisms of action of IVIG. Because of the expense and relative scarcity of large amounts of purified, pooled normal IgG, this form of therapy should be used only for selected illnesses for which other treatment is ineffective.

The many faces of scleroderma.

This review integrates the clinical aspects of systemic sclerosis (SSc; scleroderma) and scleroderma-like conditions with new knowledge of the control of blood vessel tone and the role of anoxia in the activation of connective tissues leading to fibrosis. Serologic tests, high resolution computed tomographic scanning, bronchoalveolar lavage, and physiologic assessment of pulmonary gas diffusion are compared as diagnostic tools and as means of quantitating internal organ involvement. Treatment of Raynaud's disease and phenomenon, management of scleroderma renal crisis, and new means for improving gastrointestinal function with octreotide, the somatostatin analogue, also are discussed. The relationship between idiopathic forms of SSc and eosinophilic fasciitis/eosinophilia-myalgia syndrome caused by L-tryptophan ingestion and the scleroderma-like disease associated with silicone breast implants also is discussed.

The role of infections in the rheumatic diseases: molecular mimicry between bacterial and human stress proteins?

Infections can cause or exacerbate the rheumatic diseases in several ways, including immune cross-reactivity between bacterial heat shock proteins and similar proteins in normal human tissues. This may lead to autoimmunity in rheumatoid arthritis and systemic lupus. In addition, increased activation of the gene regulating the synthesis of a heat shock protein has been found in scleroderma fibroblasts. As an infection-induced model for other rheumatic diseases, rheumatic fever (RF), with its well-established link to prior group A streptococcal infection, will be revisited. The lessons learned from RF and other rheumatic diseases directly linked to infection will be applied to ankylosing spondylitis, rheumatoid arthritis, Sjogren's syndrome and polymyositis, for which a mounting body of circumstantial evidence suggests a probable infectious cause. The interplay of genetic susceptibility and infection with particular organisms and the implications of this new information for present and future therapy of the rheumatic diseases will also be presented.

Synthesis of specific IgG idiotypes by rheumatoid synovium.

Synovial tissue samples from 6 patients with rheumatoid arthritis were cultured, and the IgG antibodies isolated from the synovial culture supernatants were used to immunize rabbits to make 6 antiidiotypic (anti-Id) antibody preparations. After extensive adsorption, the rabbit anti-Id were tested in a solid-phase enzyme-linked immunosorbent assay (ELISA). Each anti-Id reacted predominantly with the immunizing synovial IgG and showed almost no reactivity with either pooled normal human serum IgG or with IgG from 50 normal donors. When identical amounts of matched rheumatoid arthritis serum IgG and synovial culture supernatant IgG were probed simultaneously with the corresponding rabbit anti-Id in an ELISA, 3 of 6 pairs demonstrated an increased concentration of specific idiotypes in the synovial culture supernatant IgG. Furthermore, when these 6 matched samples were subsequently analyzed by isoelectric focusing, individual IgG antibodies in 5 of 6 synovial IgG samples revealed enhanced reactivity with the corresponding rabbit anti-Id preparations, when compared with matched serum IgG. This increased synovial concentration of specific idiotypes detected by both the ELISA and isoelectric focusing was compatible with enhanced synovial tissue synthesis of the antibodies involved. These specific Id/anti-Id reactivities were not blocked by excess normal human Fc, Fab, or F(ab')2 fragments, indicating a lack of association of the stimulating synovial antibodies with rheumatoid factors or antibodies against other IgG fragments (pepsin agglutinators).

Immune-complex vasculitis: role of complement and IgG-Fc receptor functions.

Vasculitis contributes a major component to the pathogenesis of rheumatic diseases and glomerulonephritis. A common feature of these diseases is the presence of serum immune complexes (IC) which may be deposited in blood vessel walls. The modification of the size and solubility of IC by the classical and alternative complement pathways, and the recent demonstration of the role of cellular complement receptors and IgG-Fc receptors in the handling of IC, now allow a better understanding of the pathogenesis of the severe forms of vasculitis. When complement deficiencies are present, the handling of IC is impaired, and vasculitis results. New blood tests for Factor VIII-related antigen, alkaline ribonuclease, plasma thrombospondin, and anti-neutrophil cytoplasmic antibody correlate with the presence of selected types of vasculitis. In addition, tissue thromboplastin release after application of defined tourniquet pressure can also detect subtle blood vessel injury. These new tests may allow diagnosis without risky organ biopsies. Advances in the diagnosis and treatment of vasculitis will also be discussed.

Molecular mechanisms of autoimmunity.

Autoimmune diseases result from a combination of genetic susceptibility factors and exogenous influences such as infection or chemical (including drug) exposure. Germline DNA variations in genetic type as well as defects in antigen recognition acquired during thymic education of developing T-lymphocytes both contribute to impaired self: nonself discrimination and set the stage for later development of such diseases as myasthenia gravis, polymyositis, or systemic lupus erythematosus. In addition, drugs such as D-penicillamine, hydralazine, procainamide, or quinidine induce T-cell or B-cell changes which precipitate auto-reactivity and cause drug-induced disease. Intervention in autoimmune diseases with prednisone, alkylating agents or the future use of more selective monoclonal antibody reagents may be life-saving in some of these disorders.

Effect of warfarin sodium therapy on excretion of 4-carboxy-L-glutamic acid in scleroderma, dermatomyositis, and myositis ossificans progressiva.

The effect of warfarin sodium on excretion of calcium, phosphorus, and 4-carboxy-L-glutamic acid (Gla) was studied in 5 patients with ectopic calcification (2 with scleroderma, 1 with dermatomyositis, and 2 with myositis ossificans progressiva). Warfarin reduced urinary excretion of Gla in all patients, but no changes in calcium and phosphorus excretion or in objective parameters of calcinosis were observed during 6-36 months of treatment. Two patients experienced hemorrhagic complications during therapy, emphasizing a hazard of long-term anticoagulation treatment. Since ectopic calcium deposits contain Gla-rich protein, suppression of Gla synthesis by warfarin sodium over a longer period may prevent deposition and allow removal of existing calcinosis deposits.

A restricted human antitetanus clonotype shares idiotypic cross-reactivity with tetanus antibodies from most human donors and rabbits: reactivity with antibodies of widely differing electrophoretic mobility.

Antitetanus antibodies from each of 20 hyperimmunized human donors were isolated on a tetanus immunoadsorbent, eluted with acidic buffer, and examined by isoelectric focusing (IEF). There was electrophoretic restriction, as determined by IEF, in the IgG of only 20% of the purified antibodies studied. The remaining 80% showed a more diffuse polyclonal spectrotype. Several IEF bands from the most electrophoretically restricted sample were isolated and used to immunize rabbits. Virtually every IgG-IEF band in the antitetanus antibodies of the original donor shared idiotypic cross-reactivity as detected by one or more of the three rabbit anti-Id reagents, even though major qualitative differences in binding from one rabbit anti-Id reagent to another were noted. Antitetanus antibodies of each of the 20 donors were separated by IEF and transferred to a nitrocellulose membrane. By using a sensitive and specific ELISA detection method, cross-reactivity was detected with the rabbit anti-Id reagents in 1 to 50% of the antitetanus antibodies of individual donors. This cross-reactivity was greater than 10% in 15 of the 19 antisera studied. In addition, these cross-reactive antibodies had very different electrophoretic mobility. Binding of the rabbit anti-Id reagents to the tetanus antibodies was almost completely blocked by pretreatment with soluble tetanus toxoid antigen. This idiotypic cross-reactivity with antibodies of different electrophoretic mobility from the same and unrelated donors suggests sharing among these antibodies of one or more of the germ-line DNA-encoded hypervariable regions present in the antibody-combining site.

Synthesis of electrophoretically restricted IgG by cultured rheumatoid synovium.

IgG synthesized by excised rheumatoid (RA) synovia was separated according to isoelectric point using chromatofocusing and isoelectric focusing. Over 30% of the IgG synthesized by 9 of 11 synovia had an isoelectric point greater than 8 (cathodal shift), while 55% of the synovia secreted IgG showing oligoclonal banding by isoelectric focusing. Oligoclonal serum IgG was seen in 17% of RA patients and in only 3% of hospitalized patients without RA. These results emphasize the selective character of the antigenic stimulus of the RA synovial lymphoid infiltrate.

Immunoglobulin G3 subclass production by rheumatoid synovial tissue cultures.

The cellular infiltrate in the deeper layers of the rheumatoid synovium produces a substantial amount of immunoglobulin (Ig)G. Culture supernatants of synovial tissues from 31 patients with rheumatoid arthritis (RA) undergoing joint replacement or synovectomy have been analyzed for the subclass of IgG present. IgG3 was measured by separation with Staphylococcal Protein A chromatography, precipitation with specific anti-IgG3 antibody, and differential separation of IgG3 heavy chains using polyacrylamide gel electrophoresis. IgG from RA synovial cultures contained an average of 41% IgG3 (range, 8-97%) compared with 12% IgG3 (range, 6-17%) in the serum IgG of the same patients. A group of non-RA control lymphoid tissues (four lymph nodes and five tonsils) produced 23% of total IgG as the IgG3 subclass (range, 16-35%). An average of only 9% of the synovial IgG showed aggregation compatible with IgG-rheumatoid factor (IgG-RF). Purified IgG from some of the RA synovial culture supernatants also showed significant restriction when separated by isoelectric focusing. This restriction and the enrichment for the IgG3 subclass in the IgG from RA synovial cultures suggest that either an antigen in the inflamed joint is selectively stimulating an antibody in this subclass, or that significantly differences in the catabolic rate of this subclass are found in cultures of synovial tissue when compared with that occurring in intact patients.

Protein synthesis in rheumatoid synovial tissue.

1. Function of synoviocytes and other cells in the synovium A. Histologic Considerations 1. Electron microscopic studies 2. In vivo and in vitro phagocytosis studies 3. Fluorescent antibody staining B. Culture techniques 1. Problems posed by study of isolated cells 2. Long-term explant cultures 3. Advantages of short-term incubations of synovial fragments 4. Isolation of immunoglobulins C. Non-Immunoglobulin Products of the Synovium 1. Products of normal synovium 2. Alterations induced by rheumatoid arthritis II. The Local Immune response in Rheumatoid Synovitis A. Evidence for Active Immune Stimulation 1. Meditators of cellular immunity in synovial fluid 2. Effect of synovectomy 3. Type and amount of immunoglobulin produced B. Local Commitment of Antibody Response 1. Effect of exogenous immunization 2. Rheumatoid factors. 3. Pepsin agglutinators C. 1. Relative enrichment for IgG-3 subclass 2. Increase in lambda-light chain composition III. Pathogenetic Considerations in Rheumatoid Arthritis A. Comparison of Rheumatoid versus Experimental Immune Synovitis 1. Chronic synovitis as a local immune response. 2. Role of cartilage complexes in substaining chronic synovitis B. Significance of the Restriction in the Immunoglobulin Response in Rheumatoid Arthritis 1. Analogy with other disease states in man 2. Common antigen in RA?

Cutaneous necrotizing vasculitis and related disorders.

Leukocytoclastic vasculitis of the skin comprises several distinct clinical syndromes, each with immune complex deposition and some form of complement activation. Necrotizing vasculitides of larger blood vessels also produce skin lesions. These can be distinguished morphologically from those of small vessel vasculitis. Analysis of the features of these lesions is discussed.

Electron microscopic demonstration of immunoglobulin deposition in rheumatoid cartilage.

Horseradish peroxidase (HRPO) conjugated with goat antihuman IgG, goat antihuman IgM, and aggregated human IgG has been used as a enzymatic marker to stain IgG, IgM, and rheumatoid factor in rheumatoid cartilage. When Hrpo-anti IgG and HRPO-anti IgM were used, immunoglobulin deposits were not observed in nonrheumatoid cartilage. However 7 of 8 rheumatoid cartilage specimens stained with HRPO-anti IgG showed electron-dense deposits. Three rheumatoid specimens stained with HRPO-anti IgM showed similar findings. Both of 2 rheumatoid specimens also stained positively with HRPO conjugated with aggregated IgG, a finding indicating that rheumatoid factor was present. The deposits were seen between the collagen fibers of the superficial layer of the cartilage to a maximal depth of 22 mu from the surface (average: 7 mu). The amorphous fibrinous material on the surface of the cartilage was also stained. The demonstration of IgG, IgM, and rheumatoid factor in the superficial zone of rheumatoid cartilage suggests that immune complexes are deposited in the cartilage in this disease.