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

Effects of Intravenous Immunoglobulins on Human Innate Immune Cells: Collegium Internationale Allergologicum Update 2024

BACKGROUND

Intravenous immunoglobulin (IVIg) has been used for almost 40 years in the treatment of autoimmune and systemic inflammatory diseases. Numerous cells are involved in the innate immune response, including monocytes/macrophages, neutrophils, dendritic cells, mast cells, basophils, eosinophils, natural killer cells, and innate lymphoid cells. Many studies have investigated the mechanisms by which IVIg down-modulates inflammatory and autoimmune processes of innate immune cells. However, questions remain regarding the precise mechanism of action in autoimmune or inflammatory conditions. The aim of this work was to review the immunomodulatory effect of IVIg on only human innate immune cells. A narrative review approach was chosen to summarize key evidence on the immunomodulatory effects of commercially available and unmodified IVIg on human innate immune cells.

SUMMARY

Numerous different immunomodulatory effects of IVIg have been reported, with some very different effects depending on the immune cell type and disease. Several limitations of the different studies were identified. Of the 77 studies identified and reviewed, 29 (37.7%) dealt with autoimmune or inflammatory diseases. Otherwise, the immunomodulatory effects of IVIg were studied only in healthy donors using an in vitro experimental approach. Some of the documented effects showed disease-specific effects, such as in Kawasaki disease. Various methodological limitations have also been identified that may reduce the validity of some studies.

KEY MESSAGE

As further insights have been gained into the various inflammatory cascades activated in immunological diseases, interesting insights have also been gained into the mechanism of action of IVIg. We are still far from discovering all the immunomodulatory mechanisms of IVIg.

Intravenous Immunoglobulin in Kawasaki Disease-Evolution and Pathogenic Mechanisms

Kawasaki disease (KD) is an acute vasculitis of childhood that affects the medium vessels with a special predilection to the involvement of coronary arteries. The major morbidity of this disease is due to coronary artery aneurysm, which occurs in about 25-30% of untreated cases. For decades now, intravenous immunoglobulin (IVIg) has consistently been shown to reduce the risk of CAAs to less than 5%. However, the mechanism of immunomodulation remains unclear. Several studies on the role of IVIg in the modulation of toll-like receptor pathways, autophagy, and apoptosis of the mononuclear phagocytic system, neutrophil extracellular trap, and dendritic cell modulation suggest a modulatory effect on the innate immune system. Similarly, certain studies have shown its effect on T-cell differentiation, cytokine release, and regulatory T-cell function. In this review, we discuss the potential mechanisms underlying the immunomodulatory actions of IVIg in patients with Kawasaki disease. Furthermore, we provide a summary of the evidence regarding various infusion protocols and dosages utilized in the treatment of KD patients.

Intravenous Immunoglobulins as Immunomodulators in Autoimmune Diseases and Reproductive Medicine

Intravenous administration of immunoglobulins has been routinely used for more than 60 years in clinical practice, developed initially as replacement therapy in immunodeficiency disorders. Today, the use of intravenous immunoglobulins (IVIGs) is embedded in the modern algorithms for the management of a few diseases, while in most cases, their application is off-label and thus different from their registered therapeutic indications according to the summary of product characteristics. In this review, we present the state-of-the-art use of IVIGs in various autoimmune conditions and immune-mediated disorders associated with reproductive failure, as approved therapy, based on indications or off-label. IVIGs are often an alternative to other treatments, and the administration of IVIGs continues to expand as data accumulate. Additionally, new insights into the pathophysiology of immune-mediated disorders have been gained. Therefore, the need for immunomodulation has increased, where IVIG therapy represents an option for stimulating, inhibiting and regulating various immune processes.

Pediatric Rheumatologic Effects of COVID-19

A multisystem inflammatory syndrome (MISC) can result from COVID-19 infection in previously healthy children and adolescents. It is potentially life threatening and is treated initially with intravenous immunoglobulin and aspirin but may require anti-inflammatory monoclonal antibody treatment in severe cases. SARS-CoV-2 infection can cause macrophage activation syndrome, chilblains, and flares of existing rheumatologic diseases. The pandemic has led to later presentation of some rheumatologic conditions as parents and patients have avoided health care settings. PubMed and Google scholar have been utilized to review the literature on the rheumatologic conditions resulting from COVID-19 and the current treatment options.

High Dose Intravenous IgG Therapy Modulates Multiple NK Cell and T Cell Functions in Patients With Immune Dysregulation

Intravenous immunoglobulin (IVIG) is an effective immunomodulatory treatment for immune dysregulation diseases. However, the mechanisms by which it reduces systemic inflammation are not well understood. NK cell cytotoxicity is decreased by IVIG in women with reduced fertility, but IVIG effects on NK cells in immune dysregulation are less clear. We hypothesized that IVIG modulation of lymphocyte function, especially in NK cells, is important for resolution of inflammation. Our aim was to identify IVIG-induced changes in a cohort of patients with Kawasaki disease (KD) and those that occur broadly in pediatric patients with various immune dysregulatory diseases. Peripheral blood mononuclear cells (PBMCs) of patients with KD or autoimmune/inflammatory diseases were phenotyped pre and post high dose IVIG treatment by flow cytometry. In KD patients, after IVIG infusion T_reg cell frequency and the proportion of activated CD25⁺ immunoregulatory CD56^bright NK cells was increased, and multiple lymphocyte subsets showed increased expression of the lymphoid tissue homing receptor CD62L. Importantly, IVIG treatment decreased the frequency of cells expressing the degranulation marker CD107a among cytotoxic CD56^dim NK cells, which was reflected in a significant reduction in target cell killing and in decreased production of multiple pro-inflammatory mediators. Interestingly, the activating receptor CD336 was expressed on a higher proportion of CD56^bright NK cells after IVIG in both KD and autoimmune/inflammatory patients while other NK receptors were increased differentially in each cohort. In autoimmune/inflammatory patients IVIG induced the proliferation marker CD71 on a higher percentage of CD56^dim NK cells, and in contrast to KD patients, CD107a⁺ cells were increased in this subset. Furthermore, when PBMCs were stimulated ex vivo with IL-2 or Candida antigen in autologous plasma, more of the CD4⁺ T cells of KD patients expressed CD25 after IVIG therapy but fewer cytotoxic T cells were degranulated based on CD107a expression. In summary, IVIG treatment in patients with immune dysregulation has multiple effects, especially on NK cell subsets and CD4⁺ T cells, which are compatible with promoting resolution of inflammation. These novel findings provide insight into the immunomodulatory actions of IVIG in autoimmune and inflammatory conditions.

Antibody Therapy: From Diphtheria to Cancer, COVID-19, and Beyond

The dawn of the 20th century saw the formative years of developments in immunology. In particular, immunochemistry, specifically pertaining to antibodies, was extensively studied. These studies laid the foundations for employing antibodies in a variety of ways. Not surprisingly, antibodies have been used for applications ranging from biomedical research to disease diagnostics and therapeutics to evaluation of immune responses during natural infection and those elicited by vaccines. Despite recent advancements in cellular immunology and the excitement of T cell therapy, use of antibodies represents a large proportion of immunotherapeutic approaches as well as clinical interventions. Polyclonal antibodies in the form of plasma or sera continue to be used to treat a number of diseases, including autoimmune disorders, cancers, and infectious diseases. Historically, antisera to toxins have been the longest serving biotherapeutics. In addition, intravenous immunoglobulins (IVIg) have been extensively used to treat not only immunodeficiency conditions but also autoimmune disorders. Beyond the simplistic suppositions of their action, the IVIg have also unraveled the immune regulatory and homeostatic ramifications of their use. The advent of monoclonal antibodies (MAbs), on the other hand, has provided a clear pathway for their development as drug molecules. MAbs have found a clear place in the treatment of cancers and extending lives and have been used in a variety of other conditions. In this review, we capture the important developments in the therapeutic applications of antibodies to alleviate disease, with a focus on some of the recent developments.

Evaluation of T cell cytokines and their role in recurrent miscarriage

Recurrent miscarriage (RM) is defined as two or more consecutive pregnancy losses that affect approximately 5% of conceived women worldwide. RM is a multi-factorial reproductive problem and has been associated with parental chromosomal abnormalities, embryonic chromosomal rearrangements, uterine anomalies, autoimmune disorders, endocrine dysfunction, thrombophilia, life style factors, and maternal infections. However, the exact cause is still undecided in remaining 50% of cases. Immunological rejection of the embryo due to exacerbated maternal immune reaction against paternal embryonic antigens has been set forth as one of the significant reason for RM. The accurate means that shield the embryo during normal pregnancy from the attack of maternal immune network and dismissal are inadequately implicit. However, it is suggested that the genetically irreconcilable embryo escapes maternal immune rejection due to communication among many vital cytokines exuded at maternal-embryonic interface both by maternal and embryonic cells. Previous investigations suggested the Th1/Th2 dominance in altered immunity of RM patients, according to which the allogenic embryo flees maternal T cell reaction by inclining the Th0 differentiation toward Th2 pathway resulting into diminished pro-inflammatory Th1 immunity. However, recently pro-inflammatory Th17 cells and immunoregulatory Treg cells have been discovered as essential immune players in RM besides Th1/Th2 components. Cytokines are believed to develop a complicated regulatory network so as to establish a state of homeostasis between the semi-allogenic embryo and the maternal immune system. However, an adverse imbalance among cytokines at maternal-embryonic interface perhaps due to their gene polymorphisms may render immunoregulatory means not enough to re-establish homeostasis and thus may collapse pregnancy.

The rs1051931 G>A Polymorphism in the PLA2G7 Gene Confers Resistance to Immunoglobulin Therapy in Kawasaki Disease in a Southern Chinese Population

Background: Kawasaki disease (KD) is a common cardiovascular disease in infants and young children, with fever, rash, and conjunctivitis as the main clinical manifestations, which can lead to the occurrence of coronary aneurysms. Intravenous immunoglobulin (IVIG) is the preferred treatment for KD patients, but 10-20% of patients are resistant to IVIG. Lipoprotein-associated phospholipase A 2 (Lp-PLA2) is a potential therapeutic target for coronary atherosclerotic heart disease, and the polymorphism of Phospholipase A2 Group VII (PLA2G7) is closely related to the activity of Lp-PLA2, of which rs1051931 is the strongest. Therefore, the rs1051931 polymorphism may be a predictor of IVIG resistance in KD patients. Methods: A total of 760 KD cases, including 148 IVIG-resistant patients and 612 IVIG-responsive patients, were genotyped for rs1051931 in PLA2G7, we compared the effects of rs1051931 on IVIG treatment in KD patients by odds ratios (OR) and 95% confidence interval (CI). Results: The homozygous mutation AA may be a protective factor for IVIG resistance in KD patients (adjusted OR = 3.47, 95% CI = 1.14-10.57, P = 0.0284) and is more evident in patients with KD aged <60 months (adjusted OR = 3.68, 95% CI = 1.10-12.28, P = 0.0399). Conclusions: The PLA2G7 rs1051931 G>A polymorphism may be suitable as a biomarker for the diagnosis or prognosis of IVIG resistance in KD in a southern Chinese population.

IVIG-mediated effector functions in autoimmune and inflammatory diseases

Intravenous immunoglobulin (IVIG) is a pooled preparation of normal IgG obtained from several thousand healthy donors. It is widely used in the immunotherapy of a large number of autoimmune and inflammatory diseases. The mechanisms of action of IVIG are complex and, as discussed in this review, experimental and clinical data provide an indicator that the therapeutic benefit of IVIG therapy is due to several mutually non-exclusive mechanisms affecting soluble mediators as well as cellular components of the immune system. These mechanisms depend on Fc and/or F(ab')2 fragments. A better understanding of the effector functions of IVIG should help in identification of biomarkers of responses to IVIG in autoimmune patients.

The immunomodulatory effects of intravenous immunoglobulin therapy in Kawasaki disease

The introduction of intravenous immunoglobulin (IVIG) for modulation of inflammation in acute Kawasaki disease was a great therapeutic triumph. However, three decades later, the mechanisms underlying immune regulation by IVIG are only beginning to be revealed. Stimulation of an immature myeloid population of dendritic cells that secretes IL-10 and the elucidation of Fc-specific natural regulatory T cells provide insights into the mechanisms of IVIG. Other potential mechanisms include provision of agent-specific neutralizing antibody, anti-idiotype and anti-cytokine antibodies, blockade of activating Fcγ receptors and stimulation of the inhibitory FcγRIIb receptor. New initiatives must seek to understand the mechanisms of IVIG in order to replace it one day with more affordable and more targeted therapies.

Role of Natural Killer Cells in Intravenous Immunoglobulin-Induced Graft-versus-Host Disease Inhibition in NOD/LtSz-scidIL2rg(-/-) (NSG) Mice

Although clinical studies have yet to demonstrate clearly the use of intravenous immunoglobulin (IVIG) for prevention of graft-versus-host disease (GVHD), their effective use in a xenogeneic mouse model has been demonstrated. We aimed to determine the mechanism of action by which IVIG contributes to GVHD prevention in a xenogeneic mouse model. NOD/LtSz-scidIL2rg(-/-) (NSG) mice were used for our xenogeneic mouse model of GVHD. Sublethally irradiated NSG mice were injected with human peripheral blood mononuclear cells (huPBMCs) and treated weekly with PBS or 50 mg IVIG. Incidence of GVHD and survival were noted, along with analysis of cell subsets proliferation in the peripheral blood. Weekly IVIG treatment resulted in a robust and consistent proliferation of human natural killer cells that were activated, as demonstrated by their cytotoxicity against K562 target cells. IVIG treatment did not inhibit GVHD when huPBMCs were depleted in natural killer (NK) cells, strongly suggesting that this NK cell expansion was required for the IVIG-mediated prevention of GVHD in our mouse model. Moreover, inhibition of T cell activation by either cyclosporine A (CsA) or monoclonal antihuman CD3 antibodies abolished the IVIG-induced NK cell expansion. In conclusion, IVIG treatment induces NK cell proliferation, which is essential for IVIG-mediated protection of GVHD in our mouse model. Furthermore, activated T cells are mandatory for effective IVIG-induced NK cell proliferation. These results shed light on a new mechanism of action of IVIG and could explain why the efficacy of IVIG in preventing GVHD in a clinical setting, where patients receive CsA, has never been undoubtedly demonstrated.

Intravenous immunoglobulin attenuates experimental autoimmune arthritis by inducing reciprocal regulation of Th17 and Treg cells in an interleukin-10-dependent manner

OBJECTIVE

Intravenous immunoglobulin (IVIG) is used as a therapeutic agent in various autoimmune diseases. The aims of this study were to investigate the therapeutic effects of IVIG on collagen-induced arthritis (CIA) and identify the mechanism responsible for any therapeutic effects.

METHODS

IVIG was administered to mice with CIA, and the in vivo effects were determined. Th17 and Treg cell frequencies were analyzed by flow cytometry, and cytokine levels in the supernatant were measured by enzyme-linked immunosorbent assay. Subpopulations of T cells and B cells in the spleen were assessed by confocal microscopy.

RESULTS

The arthritis severity score and incidence of arthritis were lower in mice treated with IVIG compared with untreated mice. Histopathologic analysis showed less joint damage in mice treated with IVIG. The expression of proinflammatory cytokines, specific type II collagen antibodies, and osteoclast markers was significantly reduced in mice treated with IVIG. Administration of IVIG induced increased FoxP3 expression and inhibited Th17 cell development. The number of FoxP3+ Treg cells was increased, and the number of Th17 cells was decreased in the spleens of mice treated with IVIG. The number of FoxP3+ follicular helper T cells was increased, and subsequent maturation of germinal center B cells was inhibited by IVIG. In addition, IVIG up-regulated interleukin-10 (IL-10) and Fcγ receptor IIB expression. The treatment effects of IVIG on arthritis were lost in IL-10-knockout mice.

CONCLUSION

These results showed that IVIG has therapeutic effects by modulating CD4+ T cell differentiation. The therapeutic effects of IVIG are dependent on IL-10.

Polyclonal and monoclonal antibodies in clinic

Immunoglobulins (Ig) or antibodies are heavy plasma proteins, with sugar chains added to amino-acid residues by N-linked glycosylation and occasionally by O-linked glycosylation. The versatility of antibodies is demonstrated by the various functions that they mediate such as neutralization, agglutination, fixation with activation of complement and activation of effector cells. Naturally occurring antibodies protect the organism against harmful pathogens, viruses and infections. In addition, almost any organic chemical induces antibody production of antibodies that would bind specifically to the chemical. These antibodies are often produced from multiple B cell clones and referred to as polyclonal antibodies. In recent years, scientists have exploited the highly evolved machinery of the immune system to produce structurally and functionally complex molecules such as antibodies from a single B clone, heralding the era of monoclonal antibodies. Most of the antibodies currently in the clinic, target components of the immune system, are not curative and seek to alleviate symptoms rather than cure disease. Our group used a novel strategy to identify reparative human monoclonal antibodies distinct from conventional antibodies. In this chapter, we discuss the therapeutic relevance of both polyclonal and monoclonal antibodies in clinic.

Immunoglobulin treatment for severe childhood epilepsy

We have used intravenous immunoglobulin to treat pediatric patients with various severe epileptic conditions. This retrospective, multicenter study comprised 64 consecutive patients treated with immunoglobulins for either epileptic encephalopathy or refractory epilepsy. The rate of full or partial improvement according to specific syndrome involved three of four patients with idiopathic West syndrome, six of 12 patients with electrical status epilepticus in sleep, eight of 19 patients with an undefined syndrome, one of three patients with Landau-Kleffner syndrome, and one of two patients with Rasmussen encephalitis. Intravenous immunoglobulins were ineffective in 10 patients with symptomatic West syndrome, nine with febrile infection-related status epilepticus, three with myoclonic astatic epilepsy, and two with Lennox-Gastaut syndrome. Nine patients (14%) demonstrated complete resolution, and 10 (15.6%) exhibited partial improvement. Of these 19 responders (29.7%), eight relapsed. Although intravenous immunoglobulin is not suitable for all cases of epilepsy, it may prove efficacious for specific epileptic syndromes, mainly idiopathic West syndrome and electrical status epilepticus during sleep.

Intravenous immunoglobulin therapy in intractable childhood epilepsy: open-label study and review of the literature

Our aim was to investigate the long term effectiveness of intravenous immunoglobulin (IVIG) against intractable childhood epilepsy in the era of new antiepileptics and to determine the predictors of a favorable response in a prospective open-label add-on study. Of thirty-seven 9.9+/-0.9-year-old patients (11 with partial seizures, 26 with generalized seizures of whom 9 had West syndrome and 17 Lennox-Gastaut syndrome) followed for 15+/-3 months, 43% had a >50% decrease in seizures (including 15% seizure free, 229+/-58 compared with 104+/-3 seizures/month, P=0.035: generalized 246+/-318 to 117+/-200, P=0.025, partial 191+/-437 to 72+/-179, P>0.05; power=0.2). Males were more likely to respond than females (P=0.011, odds ratio=9.3). Review of the literature revealed nine other articles reporting efficacy of IVIG against epileptic seizures. Only one other used statistical methods and, unlike ours, showed only a trend toward seizure frequency reduction without achieving statistical significance, presumably because it was underpowered. These results indicate large-scale controlled studies of IVIG in epilepsy are still needed.

Comèl-Netherton syndrome defined as primary immunodeficiency

BACKGROUND

Mutations in serine protease inhibitor Kazal-type 5 (SPINK5), encoding the serine protease inhibitor lympho-epithelial Kazal-type 5 related inhibitor (LEKTI), cause Comèl-Netherton syndrome, an autosomal-recessive disease characterized by congenital ichthyosis, bamboo hair, and atopic diathesis. Despite increased frequency of infections, the immunocompetence of patients with Comèl-Netherton syndrome has not been extensively investigated.

OBJECTIVE

To define Comèl-Netherton syndrome as a primary immunodeficiency disorder and to explore the benefit of intravenous immunoglobulin replacement therapy.

METHODS

We enrolled 9 patients with Comèl-Netherton syndrome, sequenced SPINK5, and analyzed LEKTI expression by immunohistochemistry. Immune function was assessed by measuring cognate immunity, serum cytokine levels, and natural killer cell cytotoxicity.

RESULTS

All patients presented with recurrent skin infections caused predominantly by Staphylococcus aureus. All but 1 reported recurrent respiratory tract infections; 78% had sepsis and/or pneumonia; 67% had recurrent gastrointestinal disease and failure to thrive. Mutations in SPINK5-including 6 novel mutations-were identified in 8 patients. LEKTI expression was decreased or absent in all patients. Immunologic evaluation revealed reduced memory B cells and defective responses to vaccination with Pneumovax and bacteriophage phiX174, characterized by impaired antibody amplification and class-switching. Immune dysregulation was suggested by a skewed T(h)1 phenotype and elevated proinflammatory cytokine levels, whereas serum concentrations of the chemokine (C-C motif) ligand 5 and natural killer cell cytotoxicity were decreased. Treatment with intravenous immunoglobulin resulted in remarkable clinical improvement and temporarily increased natural killer cell cytotoxicity.

CONCLUSION

These data provide new insights into the immunopathology of Comèl-Netherton syndrome and demonstrate that this multisystem disorder, characterized by lack of LEKTI expression in epithelial cells, is complicated by cognate and innate immunodeficiency that responds favorably to intravenous immunoglobulin therapy.

Hemophagocytic lymphohistiocytosis and Kawasaki disease: combined manifestation and differential diagnosis

Both hemophagocytic lymphohistiocytosis (HLH) and Kawasaki disease (KD) are diagnosed in patients with prolonged resistant fever by using a scoring system. Concurrent manifestation of both conditions has been reported previously. We describe an infant of 7 weeks whose condition fulfilled the criteria of HLH, but who, after clinical response to treatment, suddenly died from a myocardial infarction at 11 weeks. Post-mortem examination revealed a previously unknown coronary arteritis typical for KD. Since it is difficult to distinguish between KD and HLH, both diseases should be considered in young children with overlapping symptoms. Repeated echocardiograms may be helpful in these cases.

Modulation of the cellular immune system by intravenous immunoglobulin

Intravenous immunoglobulin (IVIg) is therapeutically used in a variety of immune-mediated diseases. The beneficial effects of IVIg in auto-antibody-mediated diseases can be explained by neutralization, accelerated clearance and prevention of Fcgamma-receptor binding of auto-antibodies. However, the means by which IVIg exerts therapeutic effects in disorders mediated by cellular immunity have remained enigmatic. Clinical improvements, followed by IVIg treatment, often extend beyond the half-life of infused IgG, thereby indicating that IVIg modifies the cellular immune compartment for a prolonged period. Here, we discuss recent advances in the understanding of different, mutually non-exclusive mechanisms of action of IVIg on cells of the innate and adaptive immune system. These mechanisms might explain the beneficial effects of IVIg in certain autoimmune and inflammatory diseases.

Gene-expression patterns reveal underlying biological processes in Kawasaki disease

Analysis of patterns of gene expression in peripheral blood from children with Kawasaki disease revealed dynamic and variable gene expression programs involving neutrophil activation and apoptosis.

Background

Kawasaki disease (KD) is an acute self-limited vasculitis and the leading cause of acquired heart disease in children in developed countries. No etiologic agent(s) has been identified, and the processes that mediate formation of coronary artery aneurysms and abatement of fever following treatment with intravenous immunoglobulin (IVIG) remain poorly understood.

Results

In an initial survey, we used DNA microarrays to examine patterns of gene expression in peripheral whole blood from 20 children with KD; each was sampled during the acute, subacute, and convalescent phases of the illness. Acute KD was characterized by increased relative abundance of gene transcripts associated with innate immune and proinflammatory responses and decreased abundance of transcripts associated with natural killer cells and CD8⁺ lymphocytes. There was significant temporal variation in transcript levels during the acute disease phase and stabilization thereafter. We confirmed these temporal patterns in a second cohort of 64 patients, and identified additional inter-individual differences in transcript abundance. Notably, higher levels of transcripts of the gene for carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) were associated with an increased percentage of unsegmented neutrophils, fewer days of illness, higher levels of C-reactive protein, and subsequent non-response to IVIG; this last association was confirmed by quantitative reverse transcription PCR in a third cohort of 33 patients, and was independent of day of illness.

Conclusion

Acute KD is characterized by dynamic and variable gene-expression programs that highlight the importance of neutrophil activation state and apoptosis in KD pathogenesis. Our findings also support the feasibility of extracting biomarkers associated with clinical prognosis from gene-expression profiles of individuals with systemic inflammatory illnesses.

Intravenous immunoglobulins suppress T-cell priming by modulating the bidirectional interaction between dendritic cells and natural killer cells

The modes of action of intravenous immunoglobulins (IVIgs) in exerting their immunomodulatory properties are broad and not fully understood. IVIgs can modulate the function of various immune cells, including suppressing the capacity of dendritic cells (DCs) to stimulate T cells. In the present study, we showed that DCs matured in the presence of IVIgs (IVIg-DCs) activated NK cells, and increased their interferon-γ production and degranulation. The activated NK cells induced apoptosis of the majority of IVIg-DCs. In consequence, only in the presence of NK cells, IVIg-DCs were 4-fold impaired in their T-cell priming capacity. This was due to NK-cell–mediated antibody-dependent cellular cytotoxicity (ADCC) to IVIg-DCs, probably induced by IgG multimers, which could be abrogated by blockade of CD16 on NK cells. Furthermore, IVIg-DCs down-regulated the expression of NKp30 and KIR receptors, and induced the generation of CD56brightCD16−CCR7+ lymph node–type NK cells. Our results identify a novel pathway, in which IVIgs induce ADCC of mature DCs by NK cells, which downsizes the antigen-presenting pool and inhibits T-cell priming. By influencing the interaction between DCs and NK cells, IVIgs modulate the ability of the innate immunity to trigger T-cell activation, a mechanism that can “cool down” the immune system at times of activation.

Kawasaki syndrome

Kawasaki syndrome is an acute, self-limited vasculitis that occurs in children of all ages and presents a challenge for the clinician: the disorder can be difficult to recognise; there is no diagnostic laboratory test; there is an extremely effective therapy; and there is a 25% chance of serious cardiovascular damage if the treatment is not given early in the course of the disease. This review includes discussion of the history of the syndrome, the diagnostic challenges, epidemiology, aetiology, pathology, immunopathogenesis, therapy, genetic influences, and the long-term cardiovascular sequelae.

Impaired natural and CD16-mediated NK cell cytotoxicity in patients with WAS and XLT: ability of IL-2 to correct NK cell functional defect

In this study we show that Wiskott-Aldrich syndrome protein (WASp), a critical regulator of actin cytoskeleton that belongs to the Scar/WAVE family, plays a crucial role in the control of natural killer (NK) cell cytotoxicity. Analysis of NK cell numbers and cytotoxic activity in patients carrying different mutations in the WASP coding gene indicated that although the percentage of NK cells was normal or increased, natural cytotoxicity and antibody-mediated NK cell cytotoxicity were inhibited in all patients with the classical WAS phenotype and in most patients carrying mutations associated with the X-linked thrombocytopenia (XLT) phenotype. The inhibition of NK cell-mediated cytotoxicity was associated with the reduced ability of WAS and XLT NK cells to form conjugates with susceptible target cells and to accumulate F-actin on binding. Treatment with interleukin-2 (IL-2) corrected the functional defects of NK cells by affecting their ability to bind to sensitive target cells and to accumulate F-actin. In addition, we provide information on the molecular mechanisms that control WASp function, demonstrating that binding of NK cells to sensitive targets or triggering through CD16 by means of reverse antibody-dependent cellular cytotoxicity (ADCC) rapidly activates Cdc42. We also found that WASp undergoes tyrosine phosphorylation upon CD16 or β2-integrin engagement on NK cells. (Blood. 2004;104:436-443)

Surface and cytoplasmic immunoglobulin expression in circulating B-lymphocytes in acute Kawasaki disease

Kawasaki disease (KD) is an acute vasculitis of young childhood predominantly affecting the coronary arteries. IgA plasma cells have been found to infiltrate vascular and nonvascular tissues in fatal acute KD. To determine whether IgA B-lymphocytes were increased in the peripheral blood of patients with KD, we performed three-color flow cytometry to detect surface and cytoplasmic immunoglobulin expression (IgA, IgM, IgD, and IgG) of peripheral B-lymphocytes in KD patients during the acute, subacute, and convalescent stages of illness and in age-matched febrile and afebrile pediatric controls. Surprisingly, absolute numbers of B-lymphocytes expressing IgA were found to be significantly lower in peripheral blood of acute KD patients compared with febrile and afebrile pediatric controls. These findings indicate that IgA plasma cells are not present in KD tissue as a result of excess numbers of these IgA B-lymphocytes in peripheral blood. We speculate that IgA B-lymphocytes are selectively withdrawn from the peripheral circulation into KD target tissues as part of a specific IgA immune response.

Antibodies to phosphatidylethanolamine and phosphatidylserine are associated with increased natural killer cell activity in non-male factor infertility patients

Antiphospholipid antibodies (APA) have been identified in patients with recurrent pregnancy loss and IVF failure. Of these, antiphosphatidylethanolamine (aPE) and antiphosphatidylserine (aPS) may have special significance. A link between increased natural killer cell activity (NKa+) and trophoblast cell apoptosis has also been reported. This study was undertaken to determine how the APA profile was associated with peripheral NK cell activity. We evaluated 197 female IVF candidates for APA and NKa. Eighty-nine patients (45%) were APA+ and of these, 51 (57%) were aPE/aPS+. Fifty-four patients (27%) had increased NK cell activity. Some 51% of APA+ and 78% of aPE/aPS+ patients had increased NK cell activity compared with 8% and 13% when APA and aPE/aPS tested negative respectively (P: < 0.0001). Non-male factor infertility patients were APA+ and NKa+ in 57% and 34% of cases respectively, compared with 19% and 13% if a pure male factor was present. Some 88% of aPE/aPS+, non-male factor patients had increased NK cell activity, compared with 12% who tested aPE/aPS negative (P: < 0.0001) and 25% of aPE/aPS+, isolated male factor patients (P: < 0.0001). These findings establish a direct relationship between APA (specifically aPE/aPS) and increased peripheral NK cell activity among non-male factor infertility patients. It is possible that APA do not directly cause reproductive failure but rather function as markers or intermediaries for an underlying, abnormal activation of cellular immunity.

Deficiency in circulating natural killer (NK) cell subsets in common variable immunodeficiency and X-linked agammaglobulinaemia

Absolute and relative NK cell numbers were determined in peripheral whole blood by flow cytometry in patients with common variable immunodeficiency (CVID) (n = 55) and X-linked agammaglobulinaemia (XLA) (n = 19) on regular immunoglobulin (IVIG) therapy. Absolute CD3-CD16+ NK cell numbers were significantly reduced in CVID patients (median 108/microl, range 23-815), compared with normal subjects (n = 60) (289/microl, range 56-640, P < 0.001). Total lymphocyte concentrations were significantly lower in CVID (median 1587/microl, range 523-7519) compared with normal subjects (median 2019/microl, range 1124-3149, P = 0.004), with the percentage of NK cells also being significantly decreased (median 7.5%, range 3.0-33. 0%, compared with 14.2%, range 2.6-30.8%, P < 0.001). In XLA, absolute NK cell numbers (median 140/microl, range 32-551, P < 0. 001) but not relative numbers were significantly reduced compared with normal controls. We excluded the possibility that IVIG interferes with in vitro binding of CD16 MoAbs. Further analysis of NK cell subsets showed a deficiency of both CD16+ and CD56+ cells in CVID, most marked in the CD3-CD8dim subpopulation, which may be due to increased homing of these cells to the gut. Serial studies on a small number of patients suggest that IVIG therapy has no short-term effect on NK cells, although we cannot exclude an effect with prolonged use. Although there are no obvious clinical effects of the NK depletion in CVID and XLA, this may be a factor in their predisposition to cancer.

Possible Role of Interleukin-10 (IL-10) and CD40 Ligand Expression in the Pathogenesis of Hypergammaglobulinemia in Human Immunodeficiency Virus Infection: Modulation of IL-10 and Ig Production After Intravenous Ig Infusion

The mechanisms leading to polyclonal hypergammaglobulinemia in patients with human immunodeficiency virus (HIV) infection are not well understood. In light of the important role of interleukin-10 (IL-10) and the interaction between CD40 and CD40 ligand in the normal regulation of B-lymphocyte function and Ig production, we examined these parameters in 24 HIV-infected patients. Both plasma IL-10 levels and the percentage of CD4+ and CD8+lymphocytes expressing CD40 ligand were significantly higher in the patients than in the 10 blood donor controls. Serum IgG correlated positively with circulating IL-10 levels and the percentage of CD4+ lymphocytes expressing CD40 ligand. Furthermore, a single bolus infusion of intravenous Ig (0.4 g/kg) in 8 HIV-infected patients caused a further increase in IL-10 levels in plasma and an increase in both IL-10 and IgG production in peripheral blood mononuclear cell cultures. In another patient group (Wegener’s granulomatosis) receiving a single bolus infusion of intravenous Ig, a similar increase in plasma IL-10 levels was found, suggesting that this may be a general effect of intravenous Ig. In patients with HIV infection, our data suggest that a vicious cycle may be operative where high endogenous Ig levels may enhance IL-10 production that, in turn, leads to higher Ig production.

Possible Role of Interleukin-10 (IL-10) and CD40 Ligand Expression in the Pathogenesis of Hypergammaglobulinemia in Human Immunodeficiency Virus Infection: Modulation of IL-10 and Ig Production After Intravenous Ig Infusion

The mechanisms leading to polyclonal hypergammaglobulinemia in patients with human immunodeficiency virus (HIV) infection are not well understood. In light of the important role of interleukin-10 (IL-10) and the interaction between CD40 and CD40 ligand in the normal regulation of B-lymphocyte function and Ig production, we examined these parameters in 24 HIV-infected patients. Both plasma IL-10 levels and the percentage of CD4+ and CD8+lymphocytes expressing CD40 ligand were significantly higher in the patients than in the 10 blood donor controls. Serum IgG correlated positively with circulating IL-10 levels and the percentage of CD4+ lymphocytes expressing CD40 ligand. Furthermore, a single bolus infusion of intravenous Ig (0.4 g/kg) in 8 HIV-infected patients caused a further increase in IL-10 levels in plasma and an increase in both IL-10 and IgG production in peripheral blood mononuclear cell cultures. In another patient group (Wegener’s granulomatosis) receiving a single bolus infusion of intravenous Ig, a similar increase in plasma IL-10 levels was found, suggesting that this may be a general effect of intravenous Ig. In patients with HIV infection, our data suggest that a vicious cycle may be operative where high endogenous Ig levels may enhance IL-10 production that, in turn, leads to higher Ig production.

Landau-Kleffner syndrome: consistent response to repeated intravenous gamma-globulin doses: a case report

PURPOSE

Although several treatments have been tried for Landau-Kleffner syndrome (LKS) too many patients are refractory to known therapies. We report an 8-year-old girl who failed other therapies but who had a consistent response after treatment with intravenous (i.v.) gamma-globulin.

METHODS

We monitored the girl from the age of 6 years, when she presented with a 6-month history of loss of language with normal hearing, normal brain magnetic resonance imaging (MRI), increased cerebrospinal fluid (CSF) IgG index, and an EEG showing almost continuous, predominantly left-sided spike- and slow-wave complexes. She had no clinical seizures and did not respond to consecutive trials of valproate (VPA), clonazepam (CZP), prednisone, and carbamazepine (CBZ). She received three courses of intravenous (i.v.) gamma-globulin; after each course, clinical and electrographic improvement lasted a few months. After each of the initial two courses, clinical improvement lasted 3-4 months but was followed by recurrence of the spikes on the EEG and by speech deterioration.

RESULTS

However, her last remission has been continuous for the past 16 months. Her CSF IgG index became normal after the first i.v. gamma-globulin infusion.

CONCLUSIONS

Based on our experience with this patient and on other investigators' experience, we believe that further research into immunologic mechanisms and therapies of this syndrome are warranted.

Intravenous immunoglobulin inhibits natural killer cell activity in vivo in women with recurrent spontaneous abortion

We previously reported elevation of natural killer (NK) cells in women with recurrent spontaneous abortion (RSA) of immune etiology. In this study, we investigated the effect of intravenous immunoglobulin G (IVIg) on peripheral blood NK activity in vivo in women with RSA. Blood was drawn prior to and 7-11 days after IVIg therapy in eight women with RSA. NK activity was measured using K562 as target cells for 51Cr-release assays. Serum IgG concentrations were also measured. All received 400 mg/kg/day of IVIg for 3 consecutive days. 1) Seven of eight women became pregnant. Five delivered a live born infant. Three out of five women (60%) who delivered a live born infant showed a significant inhibition of NK cytotoxicity post IVIg and the rest did not show any changes; 2) NK cytotoxicity was significantly increased in a woman who miscarried again; 3) A woman who miscarried a chromosomally abnormal fetus showed a significant inhibition of NK cytotoxicity after IVIg; and 4) Serum IgG concentration increased significantly from 9.3 +/- 3.0 mg/ml to 23.5 +/- 5.1 mg/ml post IVIg therapy. IVIg effectively inhibits peripheral blood NK activity in vivo. These results are consistent with our previous finding showing that IVIg inhibits NK cell activity in vitro. Women with RSA and elevated NK cells may benefit from IVIg treatment.

Natural Killer (NK) cell deficiency associated with an epitope-deficient Fc receptor type IIIA (CD16-II)

Susceptibility to herpes virus infections has been described in experimental animals depleted of NK cells and in patients with defective NK cell function. We have identified a child with recurrent infections, especially with herpes simplex virus, who had a decreased number of CD56(+)CD3(-) NK cells in circulation. Her NK cells expressed an altered form of the Fc receptor for IgG type IIIA (Fc gamma RIIIA or CD16-II) which was not reactive with the anti-CD16-II MoAb B73.1. Sequence analysis revealed the patient to be homozygous for a T to A substitution at position 230 of CD16-II cDNA, predicting a Leu(66) to His(66) change in the first immunoglobulin domain of CD16-II at the B73.1 recognition site. Spontaneous NK cell activity of the patient's peripheral blood mononuclear cells (PBMC) was markedly decreased, while antibody-dependent cellular cytotoxicity (ADCC) was unaffected. These results suggest that this child suffers from a defect affecting the development and function of NK cells, resulting in NK cytopenia and clinically significant immunodeficiency. The role of the CD16-II mutant in the pathogenesis of the patient's NK cell deficiency is discussed.

Immunoglobulins and left ventricular structure and function in pediatric HIV infection

BACKGROUND

Progressive left ventricular (LV) dilation is common in children infected with HIV-1 and may be a harbinger of congestive heart failure (CHF). In many HIV-infected children, dilation is associated with inadequate LV hypertrophy, elevated afterload, and reduced LV function. Because CHF has been observed empirically to improve after treatment with intravenous immunoglobulin (IVIG) in other conditions and because LV dysfunction in pediatric HIV may be immunologically mediated, we examined retrospectively the relation between immunoglobulins and LV structure and function in 49 HIV-infected infants and children without CHF.

METHODS AND RESULTS

A total of 106 echocardiograms were performed in these children within 30 days of serum immunoglobulin (IgG, IgA, and IgM) measurements; this includes 12 children treated with IVIG therapy. All echocardiographic parameters, blood pressures, and immunoglobulins were adjusted for age or body surface area and subjected to repeated-measures regression. Regression models were adjusted simultaneously for endogenous IgA, IgG, IgM, IVIG therapy, zidovudine therapy, age, HIV disease stage, and weight. Higher endogenous serum IgG levels and IVIG treatment were associated with significantly greater wall thickness and lower peak wall stress. Higher endogenous serum IgA levels were associated with more normal LV wall thickness and LV thickness-to-dimension ratios. LV contractility, fractional shortening, end-systolic wall stress, and thickness-to-dimension ratio all showed a trend toward more normal values with higher endogenous immunoglobulin values or during IVIG treatment.

CONCLUSIONS

LV structure and function appear to be more normal in HIV-infected children who receive IVIG treatment and in those with higher endogenous IgG levels. These results suggest that both the impaired myocardial growth and the LV dysfunction observed may be immunologically mediated and responsive to immunomodulatory therapy.

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.