Phase I study of intravenous gamma globulin in multiple myeloma

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.

Multiple myeloma in the elderly

While multiple myeloma is an incurable disease for nearly all patients, current chemotherapy and supportive care can result in significant disease control and improved duration of survival and quality of life. With the average age of patients about 70, most of the high-dose curative strategies exclude the bulk of patients affected by the disease. Recent advances in understanding the biology and pathophysiology of myeloma have led to novel therapies aimed at altering drug resistance, improving duration of the plateau phase, interrupting the cytokine growth stimulation, and improving management of common complications including infections, anemia, and bone lesions. These latter approaches are not restricted to younger patients, and early evidence indicates that elderly patients are also likely to benefit.

Intravenous immune globulins. A review of their uses in selected immunodeficiency and autoimmune diseases

Intravenous immune globulin (IGIV) was introduced a decade ago as a therapy for primary immunodeficiency diseases. It proved to be a valuable therapeutic substance for this purpose and is now considered to be the treatment of choice. The intent was to supply ubiquitous anti-infectious agent antibodies through passive immunisation to replace deficient circulating antibody content. During such therapy, unexpected benefits were noted in thrombocytopenic patients. Since that time, the therapeutic indications for IGIV infusions have greatly increased, with a particular interest in infectious, haematological and autoimmune diseases. This review summarises the status of IGIV therapy in haematological diseases within the categories of primary immunodeficiency diseases, secondary immunodeficiency states and autoimmune syndromes. The majority of firm data have been gathered on the treatment of patients with primary immunodeficiency disease. These data are reviewed from the aspect of anticipated therapeutic response and side effects. Emphasis should be placed on the IgG circulating blood levels as there is a need for individualizing therapy because of marked interindividual patient variation. The use of IGIV therapy in primary and secondary immunodeficiency states should consider the potential benefits to be attained in haematological malignancies and related complications which may be magnified by chemotherapy and radiation therapy. The mode of action of IGIV in autoimmune diseases, although not yet precisely determined, may involve establishing reticuloendothelial blockade or immunomodulation by supplying anti-idiotype antibodies.

Historic aspects of intravenous immunoglobulin therapy

The earliest preparations of immunoglobulins (Ig) decreased the susceptibility of agammaglobulinemic patients to infections caused by pneumococci, Haemophilus influenzae, meningococci, streptococci, and Pseudomonas aeruginosa. Intramuscular administration of such preparations was painful and traumatic, especially for children. Ethanol-fractionated Ig could not be administered intravenously (IV) because the IgG molecules tended to aggregate and thus were more likely to produce anaphylactoid reactions. New Ig preparations, isolated at low pH (e.g., pH 4) in the presence of traces of pepsin to inhibit reaggregation, were well tolerated when administered IV. Thus a new era of treatment and prophylaxis of disease using IV Ig (IVIG) was launched. The IVIG preparations revolutionized the management of virtually all immunodeficiency syndromes characterized by failure of antibody responses. Amelioration of antibody deficiency secondary to certain chronic diseases or surgical trauma can be achieved with these preparations. Newer uses of IVIG include treatment of some autoimmune diseases; in some conditions, the beneficial influences may be attributable to antiidiotype antibodies present in the IVIG. Another likely explanation is that IVIG inhibits damage to cells and tissues by antibody-mediated cellular cytotoxicity or blocks phagocytosis that is facilitated by Fc receptor mechanisms. The value of IVIG in preventing infection in patients undergoing bone marrow or organ transplantation and in the treatment and prophylaxis of life-threatening infections in neonates and premature infants also is reviewed.

Human immunoglobulin G and immunoglobulin G subclasses: biochemical, genetic, and clinical aspects

Human IgG consists of two identical heavy (H) chains and two identical light (L) chains joined by interchain disulfide bridges. Heterogeneity in the amino acid sequences of the H and L polypeptides results in at least three types of IgG variants at the structural and genetic levels. The four isotypic forms are IgG1, IgG2, IgG3, and IgG4, which share extensive homologies in the primary structure of their H chains. As a result, the subclasses cross-react antigenically, but they can be differentiated on the basis of subtle architectural dissimilarities. The biological and effector properties of the IgG isotypes have been associated, in part, with their structural differences. Genes determining the synthesis of human IgG heavy chains are located on chromosome 14. In several clinical situations the isotypes appear to be regulated or expressed in patterns reflecting the gene arrangement. The numeric designations of the subclasses correspond to the order of their proportional amounts in healthy adult serum: IgG1 greater than IgG2 greater than IgG3 greater than IgG4. Awareness of the importance of the roles of the four IgG isotypes in human health has steadily increased since they were first described in the 1960s. The recognition that deficits or increases in selected IgG subclasses may have clinical consequences has prompted considerable interest in quantifying the four isotypes in clinical specimens. In particular, deficiencies of IgG2, IgG3, and IgG4, singly or combined, are associated with chronic infections which may not be readily recognized in otherwise healthy people with normal serum total IgG concentrations. Different assay methods using polyclonal or monoclonal antisera with various calibrants have been applied; however, no standardized method exists at the present. IgG deficits are associated with gene defects and are acquired in secondary immunodeficiencies in conjunction with other disorders. IgG isotype selectivity has been recognized in autoimmune diseases and in response to carbohydrate and protein antigens derived from pathogenic microorganisms and common allergens.

Clinical uses of intravenous immune globulin: immunoglobulin replacement therapy and treatment of autoimmune cytopenias

Intravenous immune globulin (IVIG) is indicated for IgG replacement in antibody deficiency syndromes and as immunoregulatory therapy in some autoimmune diseases. Two case histories illustrate both aspects of IVIG therapy. 1. Patient 1 is a 24-year-old male with agammaglobulinemia. He was successively treated with monthly IMIG, paternal plasma, and then over the last 5 years, IVIG. On IgG doses of 250 mg/kg q/4 weeks, IgG trough levels remained below 200 mg IgG/dl. IgG half-life was reduced. Although asymptomatic for prolonged periods of time, he eventually developed clinically evident inflammatory bowel disease. Optimal IVIG replacement therapy requires normal IgG half-life and adequate IgG trough levels. 2. Patient 2 is a 12-year-old girl with autoimmune neutropenia, recurrent skin infections, and ileitis unresponsive to antibiotics and to steroid therapy. IVIG at a dose of 3,000 mg/IgG/kg over 3 days significantly increased her neutrophil count. Subsequently, she has required 1,000 mg/kg of IVIG q/4 weeks for maintenance. Antineutrophil autoantibodies have persisted. There is synergism of IVIG with high doses of corticosteroids. The mechanism of action of IVIG seems to involve a blockage of the RES system. IVIG therapy is safe even at high doses for most patients. However, anaphylactic reactions have been observed in IgA-deficient patients with IgE anti-IgA antibodies. The full spectrum of therapeutic applications of IVIG is still being explored. For some patients self-infusion of IVIG at home is an appealing treatment alternative.

Use of monoclonal antibodies to quantify subclasses of human IgG. I. Development of two-site immunoenzymometric assays for total IgG subclass determinations

Dissection of the IgG antibody response into its subclass components has been difficult largely because of the lack of adequate supplies of specific reagents. The development of monoclonal antibodies (Mcab) promises to overcome this problem, but the use of such antibodies has certain inherent problems. It has been shown recently that Mcabs which were avid, potent and specific for well defined epitopes may partially or completely lose their activity depending on the assay system in which they were used. In order to identify Mcabs that would be specific and useful as capture antibodies in a simple two-site enzymometric assay, a panel of 18 Mcabs was screened and one Mcab to each of the four IgG subclasses was identified for quantitation of subclass levels in human serum.

Multiple myeloma: current therapy and a glimpse of the future

Patients with benign monoclonal gammopathy or smouldering multiple myeloma should not be treated. The plasma cell labelling index utilizing tritiated thymidine or a monoclonal antibody to 5-bromo-2-deoxyuridine is helpful in differentiating patients with benign monoclonal gammopathy or smouldering myeloma from those with overt myeloma. Although combinations of chemotherapeutic agents seem to produce a greater number of objective responses than does melphalan-prednisone, a significant difference in survival has not been proved. Possibilities for future treatment include chemotherapy with large intravenous doses of melphalan, very small doses of cyclophosphamide or melphalan, the administration of hydroxyurea before chemotherapy, combination of interferon with alkylating agents, autologous bone marrow transplantation, and improvement of the soft-agar colony-forming assay for myeloma cells. The therapeutic use of monoclonal antibodies to plasma cell antigens may be possible in the future. Much more needs to be learned about the biologic basis of myeloma before real progress can be made.

Evaluation of thirty-one mouse monoclonal antibodies to human IgG epitopes

Stable clones of 31 mouse hybridomas that produce monoclonal antibodies (MAbs) against human IgG antigenic determinants were obtained. The number of hybridomas of different specificity described are: 2 anti-IgG1 Fc, 1 anti-IgG2 Fc, 1 anti-IgG2 Fd, 2 anti-IgG3 Fc, 2 anti-IgG3 hinge, 3 anti-IgG4 Fc, 3 anti-IgG4 Fd, 2 anti-nG4m(b), 4 anti-IgGFc, 2 anti-IgGFd, 1 anti-kappa, 1 anti-lambda, 1 anti-non IgG1, 2 anti-non IgG2, 2 anti-non-IgG3, 2 anti-non-IgG4. Evidence is presented validating their specificity. Some MAbs demonstrated to be avid, potent, and specific for well defined IgG-subclass epitopes may be partially or completely inactive in other assay systems, presumably because of different presentations of antigen epitopes. In general, this problem requires careful writing of protocols describing the use of MAbs.