Intravenous immune globulins: an update for clinicians

Review: intravenous immunoglobulin therapy and thromboembolic complications

Intravenous immunglobulin (IVIg) is used to treat a number of immune-deficiences and autoimmune diseases. Safety concerns related to a number of reported thromboembolic complications prompted us to review the literature. These complications happened mainly in individuals that had risk factors for thromboembolism, like advanced age, previous thromboembolic diseases, bed-ridden, and in individuals in which high doses or high infusion rates of IVIg were administered. The mechanism responsible for these events seems to be a rise in plasma viscosity that can trigger a thromboembolic event, especially in cases in which there is an underlying circulation impairment. Complications can be minimized by using IVIg only in clear-cut indications, weighting risk versus benefit in patients who are at high risk for thromboembolism and by sticking to carefully monitored slow infusion rates. IVIg for the treatment of autoimmune disorders should be administered as a five-day course of 2 g/kg of body weight. Each daily dose of 400 mg/kg should be given in not less than eight hours.

A cluster of parvovirus B19 infections in renal transplant recipients: a prospective case series and review of the literature

Up to 9% of renal transplant recipients have severe multifactorial erythropoietin-resistant anemia. Human parvovirus B19 (PVB19) infection can cause severe anemia and is likely underreported. Sparse information on epidemiology and management in this population exists. To address these issues, after our first index case, we modified our clinical practice to prospectively screen patients with persistent hemoglobin (Hb) <10 mg/dL for PVB19 infection after excluding common causes of anemia including erythropoietin resistance. Potentially infected patients were further evaluated by serology, qualitative polymerase chain reaction (quPCR) and bone marrow biopsy (BMB) for cytomegalovirus, Epstein-Barr virus, PVB19 and other etiologies. Over 3 months, 212 kidney recipients visited outpatient clinics. Of 52 recipients with anemia, 8 had an Hb <10 mg/dL with erythropoietin resistance and were screened for PVB19 infection. Three cases had PVB19 infection by quPCR and often-inconclusive serology/BMB results. Cases had immunosuppression reduced and received IVIG (0.5 gm/kg x 4 doses) with recovery from anemia, viral clearance in two cases and one recurrence. PVB19-mediated anemia occurred in up to three out of eight (38%) screened kidney recipients with Hb <10 mg/dL resistant to erythrypoietin. We recommend prospective risk stratification for this population, high indices of suspicion using at least qualitative techniques for diagnosis and treatment goal for viral eradication.

Adverse events associated with intravenous immunoglobulin therapy

In addition to its U.S. Food and Drug Administration (FDA) approved conditions, immune globulin intravenous (IGIV) is now being used to treat a vast array of autoimmune disorders. Some of the reasons for this overall increase in the use of IGIV include its effectiveness and safety. Despite many years of safe use, side effects and adverse reactions still occur. Common and mild side effects associated with IGIV include: headache, malaise, nausea, low-grade fever, urticaria, arthralgias, and myalgia. These symptoms typically resolve within a few days after their onset. Although rare, the serious and potentially fatal side effects include: anaphylactic reactions, aseptic meningitis, acute renal failure, stroke, myocardial infarction, and other thrombotic complications. Many of these side effects have occurred in patients who have significant, underlying risk factors for the development of the event. Thus, it is vitally important that a thorough and comprehensive medical evaluation be performed on every patient who is being evaluated for potential IGIV therapy. This evaluation can, to some extent, significantly minimize the risk of these side effects. Careful, constant, and close monitoring by trained personnel during the infusion can also result in early detection of such events. Physicians should thoroughly discuss the risks and benefits of IGIV with patients who are being considered for this therapy.

Characterization of immunoglobulin G fragments in liquid intravenous immunoglobulin products

BACKGROUND

Intravenous immunoglobulin (IVIG) products formulated as a liquid instead of a powder have become commercially available. Preferably, such liquid products should not alter after storage outside the refrigerator. Therefore, a thorough characterization of immunoglobulin G (IgG) fragmentation at various storage temperatures is required.

STUDY DESIGN AND METHODS

Storage experiments with liquid IVIG products from five manufacturers were performed at 4, 25, and 37 degrees C and IgG fragments were analyzed.

RESULTS

Storage of liquid IVIG products at 4 degrees C resulted in negligible alterations, whereas an increase of IgG fragments was observed after prolonged storage at elevated temperatures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis of five liquid IVIG products revealed three IgG fragments (12, 26, and 54 kDa) in all products. Fragments of similar molecular mass were produced upon incubations of IgG with blood-derived proteases. N-terminal amino acid sequencing revealed the cleavage site of these fragments, suggesting human neutrophil elastase to cause the 12-kDa fragment. The presence of elastase in liquid IVIG was confirmed by enzyme-linked immunosorbent assay. The origin of the 26- and 54-kDa fragments, both with an aspartic acid residue at the cleavage site, could not be determined unambiguously.

CONCLUSION

IgG fragmentation in liquid IVIG is negligible when stored in the refrigerator. Only after prolonged storage at elevated temperature does proteolytic degradation of IgG become apparent.

The effect of solvent environment on the conformation and stability of human polyclonal IgG in solution

Stability of therapeutic IgG preparations is an important issue as adequate efficacy and safety has to be ensured throughout a long shelf life. To this end, denaturation and aggregation have to be avoided. In many cases sugars are applied for stabilizing IgG in relatively high concentration (5-10%). However, certain sugars (sucrose, maltose) are responsible for adverse effects including renal failure. In this work we reassessed the effect of pH and stabilizers to optimize the solvent environment and minimize the amount of additives without endangering quality and stability. Since both biological function and aggregation depend on the conformational properties of individual IgG molecules, two sensitive and rapid physical methods were introduced to assess conformational changes and structural stability as a function of pH and addition of standard stabilizers. It was observed that the conformational stability decreases with decreasing pH, while the resistance against aggregation improves. The optimum pH range for storage is 5.0-6.0, as a compromise between conformational stability and the tendency for oligomerization. Intriguingly, additives in physiologically acceptable concentration have no effect on the thermal stability of IgG. On the other hand, glucose or sorbitol, even at a concentration as low as 1%, have significant effect on the tertiary structure as revealed by near-UV-CD spectroscopy, reflecting changes in the environment of aromatic side-chains. Although, 0.3% leucine does not increase conformational stability, it decreases the aggregation tendency even more efficiently than 1% glucose or sorbitol. Both pH and storage temperature are decisive factors for the long-term stability of IgG solutions. An increase in the dimer content was observed upon storage at 5 degrees C which was partly reverted upon incubation at 37 degrees C. Storage at temperatures higher than 5 degrees C may help to maintain an optimal proportion of dimers. Regarding the known side effects, and their limited stabilizing capacity at low concentration, it is advisable to omit sugars at intravenous immunoglobulin (IVIG) formulation. Hydrophobic amino acids give promising alternatives.

Treatment of glomerulonephritis: will we ever have options other than steroids and cytotoxics?

Glomerulonephritis refers to a collection of primary renal disorders and those secondary to a systemic disease, all characterized by inflammation within the glomerulus. Given the underlying immunologic nature of these disorders, they are routinely treated with corticosteriods and various cytotoxic agents. Although in many instances such therapies are successful, they are associated with significant morbidity; as such, alternatives are clearly necessary. Our understanding of the pathogenesis of immunologic glomerular diseases has grown remarkably, in large part from the study of rodent disease models. Fundamental to each disorder is the development of an antigen-specific immune response followed by the effector stage of inflammation. To block the immune response, antigen-specific therapy can be used to induce tolerance, such as through the use of double-stranded DNA molecules in lupus nephritis. Since other antigen systems are less well characterized, inducing a more generalized impairment in the immune response by blocking costimulatory molecules CD40-CD154 and CD28-CD80/86 is a growing approach to treat various immunologic disorders and transplantation. To reduce glomerular inflammation, a variety of effector systems have been targeted, including complement, cytokines/chemokines, adhesion molecules, and mediators of cellular proliferation. Of these, antibodies targeting C5 in the complement system, and antibody and receptor antagonists of tumor necrosis factor-alpha (TNF-alpha) have already been used in glomerular disorders with some promise. Less specific blockade of receptor-mediated events stimulated by platelet-derived growth factors and cell cycle proteins may soon be applied to glomerulonephritis. Finally, interruption of fibrosing pathways, which lead to glomerulosclerosis and interstitial fibrosis common to the end-stage of all glomerulonephritis, is the subject of intense effort which may yield effective biologic therapies. In spite of all these advances, we still are dependent on steroids and cytotoxics to treat glomerulonephritis. To get past this, we must devote significant resources to take observations made in basic research laboratories to develop therapeutics and prove their utility in human disease.

Pharmacokinetic effects of 4C9, an anti-FcRn antibody, in rats: implications for the use of FcRn inhibitors for the treatment of humoral autoimmune and alloimmune conditions

FcRn protects immune gamma globulin (IgG) from intracellular catabolism, and thereby contributes to the long plasma half-life associated with this class of antibody. The present study tested the hypothesis that 4C9, an anti-FcRn antibody, would increase the in vivo systemic clearance of a model antibody, anti-methotrexate IgG (AMI), in rats. Hybridomas secreting 4C9 and AMI were grown in serum free medium, and monoclonal 4C9 and AMI were purified via protein-G chromatography. Rats were instrumented with jugular vein cannulas 2-3 days prior to investigation, and 4C9 was administered intravenously at doses of 3, 15, and 60 mg/kg. AMI was then administered 4, 24, and 48 h after administration of 4C9. Blood samples were collected and assayed to determine AMI concentrations. The anti-FcRn antibody, 4C9, increased AMI systemic clearance in a dose-dependent manner (from 0.99+/-0.14 mg/h/kg in control animals to 1.27+/-0.05, 1.73+/-0.50, and 1.97+/-0.49 mL/h/kg in animals treated with 3, 15, and 60 mg/kg 4C9; p<0.05). These data were well-captured with an indirect-effect pharmacokinetic-pharmacodynamic model. The effect of 4C9 was found to be transient; no significant effects on AMI systemic clearance were observed when pre-treatment time was increased to 24 or 48 h. As such, the data demonstrate that 4C9, a monoclonal anti-FcRn antibody, induces a transient, dose-dependent increase in the elimination of IgG. The results suggest that FcRn inhibitors may have utility in the treatment of antibody-mediated autoimmune and alloimmune conditions.

Comparative Analysis of Antigen Specificities in the Monomeric and Dimeric Fractions of Intravenous Immunoglobulin

Intravenous immunoglobulin (IVIG) preparations are derived from the pooled plasma of thousands of healthy donors and contain a complex mix of antibodies. Depending on the formulation, IVIG preparations contain variable amounts of monomeric and dimeric IgG. The biological and therapeutic significance of these IVIG fractions is still ill defined. Kinetic analysis of monomeric and dimeric IgG isolated by size-exclusion chromatography revealed a stable monomeric versus an unstable dimeric IgG fraction tending to dissociation. Biochemical analysis by 2D gel electrophoresis and isotype analysis showed no significant differences between the fractions. In contrast, comparative analysis by immunodot, ELISA, FACS, and immunohistology of monomeric and dimeric IgG fractions showed a preferential reactivity of the dimeric IgG on a variety of both self-antigens and exoantigens.

Therapeutic intravenous immunoglobulins

Intravenous immunoglobulins (IVIg) are concentrated formulations of human IgG prepared by industrial fractionation of large pools of individual plasma donations. IVIg were developed 20 years ago for the prophylaxis support of immunodeficient patients. However, IVIg have been increasingly used since 10 years, in the treatment of many autoimmune and inflammatory diseases raising the possibility of product shortages and ever increasing costs in the near future. Surprisingly, the immunomodulatory mechanisms of action of IVIg are unclear because of the diversity and often contradictory Fc, F(ab')(2), and non-IgG-related mechanisms that have been proposed from clinical observations and from results obtained in various in vitro and in vivo experimental models. These concepts are reviewed here and we discuss in more details three areas of active research, namely the mechanisms of IVIg action in Idiopathic Thrombocytopenic Purpura (ITP), the effects of IVIg on activated B lymphocytes and the possible involvement of autoantibodies of IgG isotype (auto-IgG) in the immunomodulatory effects of IVIg. The elucidation of the mechanisms of action of IVIg is crucial for a more rationalized clinical use of IVIg and for developing substitutes for some of the immunomodulatory indications in order to ensure long-term availability of plasma-derived IVIg for immunodeficient patients.

Biological effects of induction immunosuppression

The concept of induction immunosuppression is evolving. Once used to buttress the inadequacies of past maintenance immunosuppressive regimens, it is now being used to permit effective maintenance immunosuppression using ever decreasing amounts of modern agents. In addition to lymphocyte depletion, with which it was once synonymous, it is now recognized that induction immunosuppression is associated with a host of non-depletional effects such as receptor modulation and blockade, which profoundly alter the lymphocyte's capacity to mount an effective response. Additionally, the recent focus on the effect of induction agents on antigen presenting cells and on regulatory factors controlling homeostatic repopulation may ultimately permit a safer, more refined and more effective approach to induction immunosuppression.

Emerging infections in transfusion medicine

The risk of transfusion-transmitted infectious diseases (TTIDs) has declined dramatically in high-income nations over the past 2 decades, primarily because of extraordinary success in preventing HIV and other established transfusion-transmitted viruses from entering the blood supply. Despite this achievement, TTIDs remain a public health concern, and attention is refocusing on new and emerging pathogens, such as West Nile virus, infectious proteins (the presumed cause of variant Creutzfeldt-Jakob disease), and other transmissible organisms such as bacteria and parasites. In this article the authors concentrate on this heterogeneous group of infectious agents, describe individual pathogens and the risks they pose to transfusion recipients, and comment on existing and evolving procedures that are designed to protect the blood supply from this threat.

Tetramolecular immune complexes are more efficient than IVIg to prevent antibody-dependent in vitro and in vivo phagocytosis of blood cells

Intravenous immunoglobulins (IVIg) have immunomodulatory effects in vivo and are widely used in the treatment of autoimmune diseases, such as idiopathic thrombocytopenic purpura (ITP). The mechanisms by which IVIg can prevent platelet clearance in ITP patients are not fully understood but are known to require the participation of low affinity Fcgamma receptors (FcgammaRs), which interact poorly with monomeric immunoglobulin G (IgG). Given the importance of low affinity FcgammaRs in the treatment of ITP, we hypothesized that immune complexes (IC) produced in vitro could reproduce the effects of IVIg. Small-size tetramolecular IC were prepared using mouse monoclonal anti-human IgG and human Fc fragments. The effects of tetramolecular IC and IVIg on the in vitro and in vivo inhibition of phagocytosis of opsonized blood cells were compared. The results obtained showed that tetramolecular IC were at least six times more efficient than IVIg to prevent phagocytosis of opsonized red blood cells in vitro, and clearance of platelets in the thrombocytopenic mouse model.

Interventions for preventing infection in nephrotic syndrome

BACKGROUND

Infection is one of the most common complications and still remains a significant cause of morbidity and occasionally mortality in patients, especially children with nephrotic syndrome. Many different prophylactic interventions have been used or recommended for reducing the risks of infection in nephrotic syndrome in clinical practice. Whether the existing evidence is scientifically rigorous and which prophylactic intervention can be recommended for routine use based on the current evidence is still unknown.

OBJECTIVES

To assess the benefits and harms of any prophylactic interventions for reducing the risk of infection in children and adults with nephrotic syndrome.

SEARCH STRATEGY

We searched the Cochrane Renal Group Specialised Register (January 2003), The Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 1, 2003), MEDLINE and Pre-MEDLINE (1966 - February 2003), EMBASE (1980 - February 2003), China Biological Medicine Database (CBMdisc, 1979 - December 2002), reference lists of nephrology textbooks, review articles, relevant trials and abstracts from nephrology scientific meetings without language restriction.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing any prophylactic interventions (pharmacological or non-pharmacological) for preventing any infection in children and adults with nephrotic syndrome.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed and extracted information. Information was collected on method, participants, interventions and outcomes ( appearance of infection, mortality, quality of life and adverse events).

MAIN RESULTS

Five RCTs conducted in China, including 308 children with nephrotic syndrome were identified. No trials were identified in adults. All trials compared one kind of prophylactic pharmacotherapy (IVIG, thymosin or a compound of Chinese medicinal herbs - TIAOJINING) in addition to baseline treatment with baseline treatment alone. No RCTs were identified comparing antibiotic or non-pharmacological prophylaxis, or pneumococcal vaccination. Three trials showed a significantly better effect of IVIG on preventing nosocomial or unspecified infection in children with nephrotic syndrome (RR 0.39, 95% CI 0.18 to 0.82). Thymosin and TIAOJINING were also effective for reducing the risks of infection in children with nephrotic syndrome with RR 0.50 (95%CI 0.26 to 0.97) and 0.59 (95%CI 0.43 to 0.81) respectively. No serious adverse events were reported.

REVIEWERS' CONCLUSIONS

IVIG, thymosin and TIAOJINING may have positive effects on prevention of nosocomial or unspecified infection with no obvious serious adverse events in children with nephrotic syndrome. However the methodological quality of all trials was poor, the sample sizes small and all studies were from China, and thus there is no strong evidence on the effectiveness of these interventions.