Immediate effects of intravenous IgG administration on peripheral blood B and T cells and polymorphonuclear cells in patients with myasthenia gravis

Immunoglobulin G has a role for systemic protein modulation in vivo: a new concept of protein homeostasis

The constant level of various proteins including albumin and cellular components in intravascular pool in vivo is strictly controlled by an unknown homeostatic mechanism, although there are fluctuations seen in pathologic conditions. Because the majority of the IgG in the serum is regarded as self-reactive natural autoantibodies, IgG may have a role to react with all proteins in vivo. It is hypothesized that like an immune system, a homeostatic mechanism for the protein pool also has a sensitive role to identify and memorize the extent and repertoire of both normal and pathogenic proteins on an individual basis, and IgG may be one of the major players in performing these functions. This hypothesis may explain the unresolved clinical observations as followed: (1) the marked increased IgG levels observed in self-limiting diseases presumed to come from immunological insults such as acute poststreptococcal glomerulonephritis and Kikuchi-Fujimoto disease, (2) an immediate reduction of all protein levels except immunoglobulins after intravenous immunoglobulin (IVIG) treatment in Kawasaki disease, (3) a unified explanation for the variety of immunomodulating effects exerted by IVIG, (4) the IgG-enzyme complexes observed in benign conditions such as macroamylasemia and hyperphosphatasemia, and (5) the marked decreased IgG level, which is correlated with the albumin level in minimal change nephrotic syndrome. IgG may be a 'watch-dog' for the disturbances of protein homeostasis in vivo. IgG may control the pathogenic proteins that appeared in disordered states, and it may help prevent the loss of proteins in case of nephrotic syndrome.

The use of intravenous immunoglobulin as maintenance therapy in myasthenia gravis

The standard therapy for myasthenia gravis (MG) includes steroids and immunosuppressants, which have delayed onset of action and significant side effects. Plasmapheresis and intravenous immunoglobulin have been used mostly for the treatment of severe exacerbations. In the present study we examined the use of intravenous immunoglobulin as maintenance treatment in MG. We included 11 patients with generalized myasthenia gravis. All had severe bulbar and respiratory involvement that required mechanical ventilation in three patients. Intravenous immunoglobulin treatment was initiated at a dose of 400 mg/kg/d for 5 days and followed by maintenance with 400 mg/kg once monthly. Regular medications were continued as necessary. There was significant improvement in all patients, and none required mechanical ventilation over the treatment period of 20.3 months +/- 8.3 (mean +/- SD, total patient years of treatment = 18.7). Steroid and pyridostigmine doses were reduced significantly and steroids were discontinued in two patients. There were no serious side effects related to intravenous immunoglobulin. These results suggest that intravenous immunoglobulin maintenance therapy is a valid modality in patients with MG.

Plasma exchange for treatment of myasthenia gravis: pathophysiologic basis and clinical experience

Myasthenia gravis is an autoimmune disease characterized by production of antibodies to acetylcholine receptors located at the motor end plate in skeletal muscles. The antibodies bind and subsequently induce degeneration of these receptors. Loss of acetylcholine receptors results in inadequate contraction of muscle fibers in response to acetylcholine released from nerve terminals and clinically apparent muscle weakness. Plasma exchange removes the circulating antibodies in myasthenic patients with short-term clinical improvement. Plasma exchange may be indicated in patients with acute exacerbation of neuromuscular weakness with bulbar or respiratory compromise, preoperative optimization prior to thymectomy, and postoperative deterioration following thymectomy or other surgical procedures. Long-term, intermittent plasma exchange for patients who do not adequately respond to standard treatment is another evolving indication.

A multicenter, randomized, double-blind, placebo-controlled trial of high-dose intravenous immunoglobulin for oral corticosteroid-dependent asthma

To determine the efficacy of high doses of intravenous gammaglobulin (IVIG) for the treatment of severe, steroid-dependent asthma in patients between 6 and 68 years of age, a randomized, double-blind, placebo-controlled multicenter clinical trial was conducted in private and university hospitals in the United States. Patients were randomized to one of three treatment arms: 2 g IVIG/kg/month (16 patients); 1 g IVIG/kg/month (9 patients); or 2 g iv albumin (placebo)/kg/month (15 patients). The treatment consisted of seven monthly infusions followed by a posttreatment observation period. The primary outcome measurement was mean daily prednisone-equivalent dose requirements, determined during the observation month preceding initiation of treatment and compared to the month preceding the seventh infusion. Secondary clinical endpoints measured were pulmonary function, frequency of emergency room visits or hospitalizations, and number of days absent from school or work. When adjusted for body weight, the mean dose requirements fell by 33, 39, and 33% in the placebo, IVIG (1 g/kg), and IVIG (2 g/kg) treatment arms, respectively. The differences between therapies were not statistically different (P = 0.9728). The mean percentage-of-predicted FEV1 fell in all three treatment groups during the treatment period but there was no significant difference between treatment groups (P = 0.8291). There was also no significant difference in the percentage of subjects requiring emergency room visits or hospitalizations or missing days of work/school, among the three treatment groups. The trial was terminated prematurely after interim analysis determined the adverse experience rate was different between the three groups. Three patients, all randomized to the 2-g/kg IVIG dose group, were hospitalized with symptoms consistent with aseptic meningitis. In summary, in this randomized, double-blind, placebo-controlled multicenter study, high doses of IVIG did not demonstrate a clinically or statistically significant advantage over placebo (albumin) infusions for the treatment of corticosteroid-dependent asthma. Subgroup analysis failed to identify markers predicting responsiveness. High-dose IVIG can also be associated with a significant incidence of serious adverse events.

Effect of high-dose intravenous immunoglobulin on serum chemistry, hematology, and lymphocyte subpopulations: assessments based on controlled treatment trials in patients with neurological diseases

The effect of intravenous immunoglobulin (IVIG) on various laboratory values was measured immediately before and after completion of serial monthly infusions of IVIG (2 g/kg) or an equal volume of placebo over 3-12 months, in 46 patients with neuromuscular diseases participating in controlled trials. Hematological, lymphocyte subpopulation, and chemistry values were analyzed and compared. After IVIG, but not placebo, a 34% reduction in lymphocytes was noted in 44/46 patients with a selective reduction of the T cells, but not the B or IL2R-positive cells. Counts returned to baseline within 30 days. Creatine kinase levels decreased by 23% and sedimentation rate increased by 275% after IVIG infusion. A nondilutional, artifactual, hyponatremia and hypomagnesemia was noted with IVIG but not placebo. We conclude that IVIG affects a variety of serum chemistry and hematological values either directly or artifactually by interfering with the laboratory method used for the assays. Transient lymphopenia is consistently seen, and may play a role in the immunomodulating effect of IVIG.

Elevated peripheral blood natural killer cells are effectively downregulated by immunoglobulin G infusion in women with recurrent spontaneous abortions

PROBLEM

We investigated the hypothesis that elevated peripheral blood natural killer cells (NK) are decreased by immunoglobulin G infusion (IVIg) therapy in women with recurrent spontaneous abortions (RSA) and elevated NK cells.

METHODS

Seventy-three women with RSA and elevated NK cells received IVIg therapy (400 mg/Kg/day for 3 days ever 4 wks) and anticoagulation treatment. Peripheral blood immunophenotype assay by flow cytometry was done prospectively prior to and 7 days after first IVIg therapy, every 2 wks until 20 wks gestation and then monthly. Controls were 95 women with RSA and normal NK cells who received anticoagulation treatment.

RESULTS

(1) 86.3% of women with elevated NK cells who received the IVIg and anticoagulation therapy had a successful pregnancy outcome; (2) Peripheral blood CD56+ NK cells and CD56+/16+ NK cells were significantly suppressed 7 days post IVIg infusion (P < 0.0005); (3) Pre-IVIg infusion levels of other lymphocyte subsets were not different as compared with those of 7 days post-IVIg therapy; (4) Women who delivered a liveborn infant with IVIg therapy demonstrated downregulation of peripheral blood NK cells (CD56+, CD56+/16+) during early pregnancy when compared to women who miscarried the index pregnancy (P < 0.05); (5) Women with normal NK cells who miscarried while on anticoagulation therapy demonstrated significantly elevated CD56+ NK cells during early pregnancy as compared with that of women who delivered a liveborn infant (P < 0.05); (6) CD19+ B cells were significantly downregulated during pregnancy in women with anticoagulation and IVIg therapy when compared to women with anticoagulation therapy (P < 0.05).

CONCLUSION

Downregulation of NK cells in women with RSA is associated with a favorable pregnancy outcome. Peripheral blood NK cells (CD56+, CD56+/16+) are effectively suppressed after IVIg therapy. Women with RSA and high NK cells benefit from IVIg therapy and experience suppression of CD56+ and CD56+/16+ NK cells.

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.

Intravenous immunoglobulins suppress the recurrences of genital herpes simplex virus: a clinical and immunological study

Effective treatment is not currently available for suppressing the recurrence of genital herpes simplex virus (HSV) infections. Since intravenous immunoglobulins (IVIG) proved useful against HSV in experimental models, we treated patients with very high frequency of HSV genital recurrences (more than 15 episodes per year) with IVIG (400 mg/Kg every fourth week). The control group was treated with intermittent oral acyclovir (800 mg twice a day for one week every month). Both groups were treated for six months and, then, patients were followed-up to further six months. Both IVIG and acyclovir were effective in reducing the frequency of HSV genital recurrences as compared to base-line. However, patients treated with IVIG had a more striking reduction in the frequency of recurrences as well as both a shorter mean duration and a minor severity of the lesions as compared to acyclovir-treated patients. Furthermore, we found a trend indicating IVIG as more effective in reducing the viral load. Since in IVIG-recipients we found a strong increase of peripheral blood lymphocytes with natural killer (NK) surface phenotype, we suggest that the clinical effectiveness of IVIG treatment is probably mediated via the expansion of NK cell populations. Our study indicates that the treatment with IVIG is an effective and safe tool for suppressing the recurrences of genital HSV infections.

[Use of immunoglobulins G in the treatment of nervous system diseases]

Short term and long term beneficial effects of IgG administration have been studied in 4 groups of neuro-immunological diseases: Polymyositis, dermatomyositis and myasthenia. Peripheral neuropathies (myelinopathies), primarily in Guillain-Barré syndrome and in chronic inflammatory polyneuropathy. Children intractable Epilepsy. Multiple Sclerosis. Actual results are in favor of an objective and marked improvement (after 1 or 2 months) in the first 2 groups using intravenous IgG. In M.S. patients, the short term treatment of bouts (especially: optic neuritis) seems promising. Results of the only one long term (later than 10 years) trial are in favor of a significant slowing of the progression of M.S. comparatively to the predictive curve of disease.

Anti-GM1 antibodies in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) treated with intravenous immunoglobulin (IVIg)

Patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and with a chronic polyneuropathy (non-CIDP) were studied for the presence of anti-GM1 antibodies. In pretreatment sera of CIDP patients, we found IgG anti-GM1 antibodies in 23%, IgM in 7%, and IgA in 14%. Predominantly motor involvement was associated with IgG and IgM anti-GM1 antibodies in CIDP patients (P = 0.002). Improvement after intravenous immunoglobulin (IVIg) therapy was not associated with anti-GM1 antibody titer before or after treatment. Anti-GM1 antibody titers before onset of treatment was not related to poor clinical outcome, although large clinical improvements after IVIg therapy were observed less often (P = 0.057) in patients with high titer anti-GM1 antibodies before treatment.

Intravenous immunoglobulins suppress immunoglobulin productions by suppressing Ca(2+)-dependent signal transduction through Fc gamma receptors in B lymphocytes

A high dose intravenous immunoglobulin (IVIG) therapy is used in the treatment of a wide range of autoimmune disorders. However, the mechanisms of the action of IVIGs remain poorly understood. To analyse the mechanisms of effects of IVIGs on immunoglobulin (Ig) production of B cells, the effects of IVIGs on B lymphoblastoid cell lines transformed by Epstein-Barr virus (LCLs) were investigated. The productions of IgG or IgM of LCLs were dose-dependently suppressed by polyethylene glycol (PEG)-treated IVIG or pH 4-treated IVIG though the productions were not or only slightly suppressed by pepsin-treated IVIG. The suppression by IVIGs was blocked by anti-human IgG Fc or anti-Fc gamma RII. C mu gene expression and mu s C terminal gene expression of LCLs were suppressed by PEG-treated IVIG, whereas neither C mu gene expression nor mu s C terminal gene expression of LCLs were suppressed by pepsin-treated IVIG. Although the increase in intracellular calcium concentration in LCLs was not suppressed by pepsin-treated IVIG, the increase was suppressed by PEG-treated IVIG. This suppressing effect of PEG-treated IVIG on intracellular calcium concentration of LCLs was blocked by anti-human IgG Fc or anti- Fc gamma RII. Our results suggest that IVIGs suppressed the Ca(2+)-dependent signal transduction through Fc gamma R on B-cell membrane, consequently, the transcription of C mu mRNA, especially secreted mu mRNA was suppressed in the B cells.

Regression of Kaposi's sarcoma after intravenous immunoglobulin treatment for polymyositis

The authors report on the case of a patient with polymyositis who was given immunosuppressive therapy and then developed Kaposi's sarcoma. Subsequently, the polymyositis was treated with high dose intravenous immunoglobulin, and the Kaposi's sarcoma regressed abruptly. The association between these two diseases and the beneficial effect of intravenous immunoglobulin on Kaposi's sarcoma are discussed.

Macrophage-megakaryocyte interaction in bone marrow after high-dose intravenous immunoglobulin therapy

Localization of IgG in bone marrow after high-dose intravenous immunoglobulin therapy (IVIG) was investigated via light and electron microscopy. IgG was incorporated into the cytoplasm of various types of bone marrow cells of all the three lineages, particularly in reticulum cells, fat cells, and megakaryocytes. In addition, both reticulum cells and fat cells showed many elongated cytoplasmic protrusions, which were in contact with the various types of blood cells, especially the megakaryocytes. A filamentous structure was also seen near the point of contact between the cells. Ultrastructural changes of macrophages in bone marrow after IVIG suggest that these cells were activated by IVIG.

Immunoregulation of Autoimmune Disorders: The Role of Intravenous Immunoglobulins

Modified and intact immunoglobulin preparations are available for therapeutic use. The administration of intravenous immunoglobulins (IVI G) gave positive results in Primary Immunodeficiency Syndromes (PIS) (prophylaxis of viral and bacterial diseases), in treatment of secondary immunodeficiencies (hematologic malignancies, bone marrow transplantation), and in some infections. Adverse reactions have been reported during IVIG infusions, but they are rarely serious and do not represent limiting conditions for a short or long term therapy. After the original observation in thrombocytopenic purpura, IVIG have been used as immune modulators in various autoimmune related disorders. Various mechanisms of action are proposed: blockade and down regulation of phagocytic function via Fc receptor, regulation of idiotype-anti idiotype network, suppression of idiotype synthesis, T-B cell interference towards antigen presentation, increase in suppressor lymphocytes, IVIG-cytokine interaction.

High-dose intravenous immunoglobulin in myasthenia gravis

The effects of high-dose intravenous immunoglobulin (i.v.Ig) in 12 MG patients were studied. All patients had severe symptoms. In two cases anti-acetylcholine receptor antibodies (anti-AChR abs) were not detectable. I.v.Ig was administered to 9 patients already on long-term immunosuppressive therapy and to 3 patients at the beginning of azathioprine treatment. 10 patients (83%) improved; the duration of improvement was longer in immunosuppressed patients. Anti-AChR abs generally decreased after infusion but we did not find a constant correlation between reduction in ab titers and clinical improvement. Side effects included one case of severe hemolysis. In our experience i.v.Ig therapy is effective in MG. The chief indication for its use appears to be the treatment of deterioration of the disease in patients already on immunosuppressive therapy.

A randomized trial comparing intravenous immune globulin and plasma exchange in Guillain-Barré syndrome. Dutch Guillain-Barré Study Group

BACKGROUND

The subacute demyelinating polyneuropathy known as Guillain-Barré syndrome improves more rapidly with plasma exchange than with supportive care alone. We conducted a multicenter trial to determine whether intravenous immune globulin is as effective as the more complicated treatment with plasma exchange.

METHODS

To enter the study, patients had to have had Guillain-Barré syndrome for less than two weeks and had to be unable to walk independently. They were randomly assigned to receive either five plasma exchanges (each of 200 to 250 ml per kilogram of body weight) or five doses of a preparation of intravenous immune globulin (0.4 g per kilogram per day). The predefined outcome measure was improvement at four weeks by at least one grade on a seven-point scale of motor function.

RESULTS

After 150 patients had been treated, strength had improved by one grade or more in 34 percent of those treated with plasma exchange, as compared with 53 percent of those treated with immune globulin (difference, 19 percent; 95 percent confidence interval, 3 percent to 34 percent; P = 0.024). The median time to improvement by one grade was 41 days with plasma exchange and 27 days with immune globulin therapy (P = 0.05). The immune globulin group had significantly fewer complications and less need for artificial ventilation.

CONCLUSIONS

In the acute Guillain-Barré syndrome, treatment with intravenous immune globulin is at least as effective as plasma exchange and may be superior.

Effect of high doses of intravenously administered immune globulin on natural killer cell activity in peripheral blood

Because Kawasaki disease is a disorder characterized by lymphocyte activation and immune complex destruction of endothelial cells, we examined the effect of administration of high doses of intravenously administered immune globulin (IVIG) on a lymphocyte population with affinity for endothelial cells: the natural killer cells. We found that administration of high doses of IVIG resulted in a significant increase in the activity of natural killer cells and in the numbers of circulating CD16+ cells. Furthermore, a study of patients treated with IVIG for seizure disorders suggests that this effect of IVIG on circulating NK cells is not unique to patients with Kawasaki disease. The beneficial effect of IVIG in the treatment of Kawasaki disease may be due to the ability of IVIG to inhibit interaction between natural killer cells and endothelial cells.

The use of IVIG in neurological disease

The studies cited herein highlight the potential benefits of IVIG therapy in a group of neurological disorders that are associated with aberrant immune responses. Indeed, all of the disorders discussed, except epilepsy, are associated with autoreactivity. The trials are preliminary and short-term and, except for idiopathic CIDP, uncontrolled. Interpretation of the findings of these uncontrolled studies is complicated by the fact that the natural history of all of these disorders is to show fluctuations. IVIG appears to be a potentially useful and safe agent in the treatment of patients with MG, intractable epilepsy, MS, and CIDP. Its place in the therapeutic approach to these neurological diseases must await the completion of controlled trials. Since other therapeutic modalities have already proven to be useful in several of these disorders, it will be important to determine if IVIG is more efficacious, safer, and more cost-effective. It is also worth considering whether the combination of IVIG and any of these more traditional approaches would provide added therapeutic benefit.

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.

Treatment of myasthenia gravis with high-dose intravenous immunoglobulin

We treated 37 patients affected by autoimmune generalized myasthenia gravis (MG) with high-dose intravenous gammaglobulin (HDIVIg), 400 mg/kg per day on 5 consecutive days. A one-degree improvement of Oosterhuis global clinical classification of myasthenic severity (OGCCMS), the disappearance of bulbar involvement or both were recorded 12 days after the beginning of the treatment in 70.3% of the patients and persisted up to 60 days in 58.7%. A two-degree improvement of OGCCMS was recorded in 54.1% of the patients and it was maintained up to 60 days in 37.8%. The percentage of improvement did not significantly differ between patients entering the treatment in a long-standing, drug-refractory stationary phase of the illness (n = 26) and patients who received HDIVIg in an acute phase of MG (n = 11). None of the patients experienced side effects. Our data indicates that HDIVIg is an interesting, virtually riskless therapeutic choice for MG patients, and allows the planning of a controlled trial versus plasma-exchange.

Use of intravenous immune globulin therapy: an overview

The intravenous immune globulin (IGIV) preparations are reviewed with respect to method of preparation, pharmacokinetics, clinical uses (with emphasis on the labeled indications), and adverse reactions; a brief review of the immune system also is provided. IGIV preparations are approved for the treatment of hypogammaglobulinemia, recurrent bacterial infections due to B-cell chronic lymphocytic leukemia, and idiopathic thrombocytopenic purpura (ITP). The mechanism of action in the first two indications is passive replacement of antibodies, but in ITP the mechanism is not clearly established. The clinical literature on the use of IGIV for these indications is summarized. In patients with ITP, platelet counts return to safe levels and the number of infections is reduced in patients with primary humoral immunodeficiency treated with IGIV. The use of IGIV in pregnant women and premature infants is controversial. Adverse reactions are primarily related to infusion rate, activation of complement, and anaphylactic reactions to a component of the product. There is minimal to no risk of viral transmission with IGIV therapy. IGIV also has been administered safely on an outpatient or homecare basis. This has led to a feeling of greater control by patients over their chronic illness. Other uses of IGIV are under investigation. As our understanding of the immune system and the pharmacology of immune globulin increases, the uses of IGIV will expand.

Suppression of immunoglobulin production of lymphocytes by intravenous immunoglobulin

The proliferative responses and the immunoglobulin production of peripheral blood mononuclear cells to pokeweed mitogen were dose-dependently suppressed by sulfonated intravenous immunoglobulin (IVIG), polyethylene glycol-treated IVIG, pH 4-treated IVIG, or human gamma-globulin, but they were not or only slightly suppressed by human serum albumin or pepsin-treated IVIG. Moreover, the suppression of immunoglobulin production by sulfonated IVIG, polyethylene glycol-treated IVIG, or pH 4-treated IVIG was seen in the cases in which B cells preincubated with IVIGs were cocultured with T cells and monocytes preincubated with or without IVIGs and in the cases in which monocytes preincubated with IVIGs were cocultured with T cells and B cells preincubated with or without IVIGs. However, in the cases in which only T cells were preincubated with IVIGs, immunoglobulin production was not suppressed. The suppression of the monocyte function by IVIGs tended to be less than the suppression of the B-cell function by IVIGs. Moreover, the suppression by IVIGs was blocked by anti-human IgG Fc. Our results suggest that IVIGs suppress the immunoglobulin production of lymphocytes through suppression of the B-cell function and the antigen presenting-cell function by attachment of IVIGs to Fc receptors of B-cell membranes and antigen presenting-cell membranes.

Intravenous gamma-globulin in myasthenia gravis: interaction with anti-acetylcholine receptor autoantibodies

Clinical improvement has been observed in myasthenia gravis patients treated by intravenous immunoglobulin (IVIg). In order to investigate the mechanism of action of these IVIg, we looked for an in vitro interaction between IVIg and the anti-acetylcholine receptor autoantibodies. Significant inhibition by IVIg of anti-acetylcholine receptor autoantibody activity from 30 MG sera was observed and binding of anti-acetylcholine receptor autoantibodies on IVIg was found for four of five myasthenia gravis sera. These observations suggest that IVIg contains Ig directly binding to and inhibiting pathogenic autoantibodies.

An open-label study of high-dose intravenous immunoglobulin in severe childhood asthma

Eight pediatric patients with severe steroid-dependent asthma were enrolled in an open-label trial of high-dose intravenous immunoglobulin (IVIG) in an attempt to decrease their steroid requirements. Monthly therapy with high-dose IVIG resulted in a threefold decrease in both maintenance oral corticosteroid dose and in extra oral corticosteroids needed for control of exacerbations of asthma. This was accompanied by significant improvements in peak expiratory flow rates and in symptom-score rating. An immunomodulatory effect of IVIG was suggested by the changes in immediate skin test reactivity. Seven of the eight patients demonstrated one or more reactions to a panel of allergens before therapy. During the course of the trial, there was a progressive diminution in skin test reactivity with a 100-fold reduction in sensitivity at the completion of 6 months of therapy. In this preliminary study, the reduction in steroid requirements, improvement in symptoms and peak flow measurements, and diminution in immediate skin test reactivity support a potential role for IVIG in the treatment of severe steroid-dependent asthma. A larger, randomized trial now appears warranted.

Intravenous immunoglobulin (IVIG) for the therapy of autoimmune disorders

The weight of evidence from numerous clinical studies supports the use of IVIG, particularly at higher doses, in the treatment of a wide range of autoimmune disorders. Extensive experience has documented the safety of IVIG therapy but its present relatively high cost necessitates firmly establishing its efficacy. There is an acute need to define those disease states where IVIG is indicated and effective. Large-scale, possibly multicentered, clinical trials employing rigorous controls will resolve these questions. Concurrent fundamental immunologic studies will elucidate the mechanisms underlying the clinical effects. We are experiencing an exciting new era of effective immunotherapies and intravenous gamma-globulin preparations have already secured an important place in the therapeutic armamentarium. While one must guard against unsubstantiated applications, critical exploration of new uses for this unique product is warranted.

Experience with intravenous immunoglobulin in myasthenia gravis

Myasthenia gravis (MG) is an acquired autoimmune disorder of neuromuscular transmission associated with a deficiency of acetylcholine receptor at the neuromuscular junction. Current therapeutic strategies are aimed at increasing the amount of acetylcholine at the neuromuscular junction or at addressing the abnormal immune response. Therapies influencing the immune response include thymectomy, corticosteroids, nonsteroidal immunosuppression, and plasmapheresis. Unfortunately, whether used alone or in combination the toxicities of these agents can be quite significant; thus, an agent with a distinct and more favorable side effect profile might be useful in MG. Intravenous immunoglobulin has such potential.

Theoretical mechanisms by which immunoglobulin therapy might benefit myasthenia gravis

The mechanisms underlying any clinical improvement observed in some patients with myasthenia gravis (MG) treated with normal immunoglobulin (Ig) are not defined. The pathologic alterations in the postsynaptic motor end plate in MG are likely due at least in part to one or more actions of antibodies against epitopes on the nicotinic acetylcholine receptor (anti-AChR Ab). Such anti-AChR Ab are secreted by B lymphocytes and are increased in the serum of MG patients but not of controls. The stimulus for anti-AChR Ab production in MG is unknown with evidence for a role of thymic abnormalities, immunoregulatory disturbances, and some possible molecular mimicry of exogenous antigens (microbial?). Postulated mechanisms underlying Ig effects in MG include: (i) competing with anti-AChR for binding to AChR; (ii) preventing attachment of Fc receptor-positive inflammatory cells to the anti-AChR Ab bound to the motor end plate; (iii) decreasing synthesis of anti-AChR Ab; and (iv) exerting an anti-idiotypic effect. Evidence for these mechanisms are discussed.

High dose intravenous gammaglobulins in autoimmune disorders: mode of action and therapeutic uses

Gammaglobulins administered intramuscularly have been used for more than 40 years to treat antibody deficiency states. In the last decade intravenous preparations were developed. They do not aggregate and contain IgG molecules with intact recognition and effector functions. These compounds are safe and only minor side effects were reported even when high doses were given. While studying their effect when given in high doses to hypogammaglobulinemic patients, an accidental finding was observed regarding their beneficial effect in idiopathic thrombocytopenic purpura (ITP). This observation led to many studies looking at the effect of high dose gammaglobulin in several other autoimmune diseases. While the effect in acute ITP is well established, there are encouraging reports in respect to the effect of intravenous gammaglobulin in many other disorders, but no final conclusion can be drawn due to the small numbers of cases studied. The mechanism by which intravenous gammaglobulin exerts its function is still unclear. It may work through the Fc receptor in the reticuloendothelial system, as an immunoregulator agent or interact in the idiotype-antiidiotype network. Intravenous gammaglobulin seems to be an important therapeutic tool in a large number of autoimmune disorders of various etiologies.