Use of intravenous immunoglobulin therapy in autoimmune blistering diseases

Autoimmune mucocutaneous blistering diseases in the south of Italy: a 25-year retrospective study on 169 patients

BACKGROUND

Autoimmune mucocutaneous blistering diseases (AMBDs) represent a heterogeneous group of organ-specific and potentially life-threatening diseases. We sought to determine the relationship between clinical remission and therapeutic regimens with clinical type and phenotype of AMBDs, as well as clinical outcomes achieved based on different therapeutic regimens.

METHODS

A retrospective single-center study on 169 AMBDs patients, including pemphigus vulgaris (PV), mucous membrane pemphigoid (MMP), paraneoplastic autoimmune multiorgan syndrome (PAMS), and lichen planus pemphigoides (LPP), was performed from 1994 to 2019 in an oral medicine tertiary center, where we collected sociodemographic data, clinical type and phenotype, prescribed therapies, and related outcomes.

RESULTS

The mean age of AMBDs patients was 55.0 ± 16.4 years. They were followed for a mean of 8.4 ± 5.8 years. The majority of these patients (62.1%) were successfully managed with conventional immunosuppressive therapy (CIST) alone. However, 37.9% of patients required additional biological treatments, either because they were non-responders or developed severe side effects from CIST, or because of the rapid and severe progression of the disease. Overall, complete clinical remission was achieved in 92.3% of patients. A statistically significant difference was noted between the frequency distribution of AMBDs patients among different therapeutic regimens (P = .002), of different clinical phenotype and type of AMBDs patients and clinical remission (P = .012 and P = .005, respectively). No difference was reported regarding clinical outcomes and different therapeutic regimens.

CONCLUSIONS

AMBDs' management may be challenging, nonetheless CIST and biologic regimens introduced, when needed as reliable alternatives to CIST, result in a very high percentage of CCR.

Ocular Manifestations and Management of Autoimmune Bullous Diseases

Autoimmune bullous diseases with ocular involvement consist of a group of systemic entities that are characterized by formation of autoantibodies against the proteins of the epithelial basement membrane zone of the conjunctiva. Mostly, the elderly are affected by these diseases. The characteristic patterns of mucocutaneous involvement and the specific tissue components targeted by these autoantibodies are differentiating features of these diseases. Ocular pemphigus vulgaris exhibits intraepithelial activity, whereas the autoimmune activity in linear immunoglobulin A disease, mucous membrane pemphigoid, and epidermolysis bullosa acquisita occurs at a subepithelial location. Given the increased risk for blindness with delays in diagnosis and management, early detection of ocular manifestations in these diseases is vital. The precise diagnosis of these autoimmune blistering diseases, which is essential for proper treatment, is based on clinical, histological, and immunological evaluation. Management usually includes anti-inflammatory and immunosuppressive medications. Inappropriate treatment results in high morbidity and even potential mortality.

Long-Term Follow-Up after Intravenous Immunoglobulin Therapy in Patients with Severe Ocular Mucous Membrane Pemphigoid Unresponsive to Conventional Therapy

Mucous membrane pemphigoid (MMP) is a heterogeneous group of rare, systemic, autoimmune subepidermal inflammatory disease that affects mucous membranes and the eye. In its most severe forms, this disease needs systemic therapy, usually based on steroids and immunosuppressant agents. In unresponsive cases or in the presence of contraindications or severe side effects due to conventional systemic corticosteroid and/or immunosuppressant therapy, a therapy shift to high-dose intravenous immunoglobulins (IVIg) has been recommended in other reports. This new therapy has proven to be effective in stopping ocular pemphigoid, but the data regarding the long-term effect on the disease activity or reactivation are extremely scarce, so the novel scientific aim of this study was to evaluate the clinical outcomes after a 9-year follow-up in 12 eyes (6 patients) affected by MMP with ocular involvement, successfully treated with IVIg therapy, as previously described in our report published in 2008. The evaluation of ocular and extraocular disease progression was performed at the end of IVIg therapy and at the end of the follow-up period. After 9 years, all the eyes enrolled showed a long-lasting remission of ocular and oral symptoms with a significant steroid-sparing effect. In conclusion, the IVIg has to be considered as a safe and successful alternative therapy in patients with severe ocular mucous membrane pemphigoid; furthermore, this kind of therapy seems to be effective in maintaining the clinical remission by the time.

Biologics in dermatology: an integrated review

The advent of biologics in dermatologic treatment armentarium has added refreshing dimensions, for it is a major breakthrough. Several agents are now available for use. It is therefore imperative to succinctly comprehend their pharmacokinetics for their apt use. A concerted endeavor has been made to delve on this subject. The major groups of biologics have been covered and include: Drugs acting against TNF-α, Alefacept, Ustekinumab, Rituximab, IVIG and Omalizumab. The relevant pharmacokinetic characteristics have been detailed. Their respective label (approved) and off-label (unapproved) indications have been defined, highlighting their dosage protocol, availability and mode of administration. The evidence level of each indication has also been discussed to apprise the clinician of their current and prospective uses. Individual anti-TNF drugs are not identical in their actions and often one is superior to the other in a particular disease. Hence, the section on anti-TNF agents mentions the literature on each drug separately, and not as a group. The limitations for their use have also been clearly brought out.

Mucous membranepemphigoid in two half-sisters. The potential roles of autoantibodies to β4 integrin subunits and HLA-DQβ1*0301

BACKGROUND

Mucous membrane pemphigoid (MMP) is a subepithelial autoimmune mucocutaneous disease. It most frequently affects the oral mucosa, followed by ocular and nasal mucosa, nasopharyngeal, anogenital, skin, laryngeal and esophageal mucosa.

MAIN OBSERVATION

Two half-sisters developed mucous membrane pemphigoid at approximately the same age. The older sister presented with primarily mucosal disease, while the younger had a more cutaneous disease. The histopathology demonstrated a subepithelial blister and direct immunofluorescence showed deposition of IgG and C3 at the basement membrane zone of perilesional tissues in both sisters. Antibodies to human β4 integrin were present in the sera of both patients and correlated with disease activity. Both sisters carried the same HLADQβ1* 0301 allele.

CONCLUSIONS

This is the first case of mucous membrane pemphigoid occurring in two half-sisters. Perhaps, it is the low incidence of mucous membrane pemphigoid that may account for the lack of reports on familial cases of the disease.

The use of intravenous immunoglobulin in autoimmune bullous diseases

Intravenous immunoglobulin (IVIG) has been shown to be effective in the treatment of autoimmune blistering diseases and may be an option if disease is refractory to conventional treatment. IVIG effectiveness appears to increase when administered concurrently with a cytotoxic drug and used in multiple treatment cycles (though a single cycle may give benefit). Tapering administration may improve the duration of remission and subcutaneous injections may be an option. This article provides an introduction to the make-up and use of IVIG, and reviews previous studies.

The use of intravenous immunoglobulin in autoimmune bullous diseases

Intravenous immunoglobulin (IVIG) has been shown to be effective in the treatment of autoimmune blistering diseases and may be an option if disease is refractory to conventional treatment. IVIG effectiveness appears to increase when administered concurrently with a cytotoxic drug and used in multiple treatment cycles (though a single cycle may give benefit). Tapering administration may improve the duration of remission and subcutaneous injections may be an option. This article provides an introduction to the make-up and use of IVIG, and reviews previous studies.

Intravenous immunoglobulins are a therapeutic option in the treatment of multiple sclerosis relapse

OBJECTIVE

The objective of the study is to evaluate the efficacy and tolerability of intravenous immunoglobulin (IVIG) monotherapy in the treatment of multiple sclerosis (MS) relapse.

BACKGROUND

High-dose intravenous methylprednisolone (IVMP) and plasmapheresis have been shown to shorten the recovery period of an MS relapse. Options for those who have contraindications for or are unresponsive to these treatments are very limited. Intravenous immunoglobulin has been used experimentally in these situations, even though there are no previous studies on its efficacy as monotherapy in MS relapse.

SUBJECTS AND METHODS

Twelve consecutive MS patients with acute MS relapse were treated with IVIG 0.4 g/kg per day for 5 days, and the next 5 patients received IVMP 1000 mg/d for 3 days. Volumetric brain magnetic resonance imaging (MRI) and clinical evaluation using expanded disability status scale (EDSS) were performed at baseline and at 3 weeks after treatment. EDSS score after 1 year of the treatment was collected from the patient records. MRI evaluation was performed blindly but not the clinical examination and EDSS scoring.

RESULTS

A significant reduction in the volumes of T2-, fluid-attenuated inversion recovery-, and gadolinium-enhanced lesions was detected in the IVIG-treated group, but not in the IVMP-treated patients. The difference between the groups did not reach statistical significance. The EDSS score improved equally in both groups.

CONCLUSIONS

Intravenous immunoglobulin did not show inferiority compared with IVMP in the treatment of an acute MS relapse evaluated clinically and radiologically. Therefore, we suggest that IVIG may be tried as a therapy in acute MS relapse, especially in case of contraindications to IVMP and plasmapheresis.

Intravenous immunoglobulin therapy in autoimmune mucocutaneous blistering diseases: a review of the evidence for its efficacy and safety

Intravenous immunoglobulin (IVIg) is a biologic agent that is being increasingly used in the treatment of autoimmune and chronic inflammatory disorders. It is approved by the US FDA for the treatment of primary immunodeficiencies, immune thrombocytopenic purpura, Kawasaki disease, bone marrow transplantation in patients aged over 20 years, chronic B-cell lymphocytic leukemia, and pediatric AIDS. IVIg has been used off-label for several diseases, clinical symptoms and syndromes. Our aim was to determine if there is evidence to support the efficacy of IVIg therapy in autoimmune mucocutaneous blistering diseases (AMBDs). We searched the PubMed database for studies on pemphigus and pemphigoid using the following criteria: (i) English language; (ii) minimum of five patients; (iii) diagnosis based on histology and immunopathology; and (iv) statistical analysis of data for comparison of efficacy provided. We evaluated the data and present information on the number of participants in each study, pre-IVIg therapy, indications for the use of IVIg, IVIg protocol (dose and interval) used, concomitant therapies, clinical outcome, follow-up period, and serologic studies. The quality of the evidence presented in this review is at Level A according to the UK National Health Service criteria. Twenty-three studies that were published between May 1999 and April 2010 were identified. One randomized controlled trial was found and all other studies were case series. Data on 260 patients treated with IVIg were analyzed: 191 patients with pemphigus and 69 patients with pemphigoid. Overall, 245 patients showed improvement with IVIg therapy. IVIg demonstrated a corticosteroid-sparing effect. In the studies presented, the incidence of serious adverse effects was not significant. The best available evidence in the literature indicates that IVIg is efficacious and has a good safety profile in the treatment of AMBDs.

High-dose intravenous immunoglobulin (IVIG) therapy in autoimmune skin blistering diseases

Treatment of autoimmune bullous skin diseases can often be challenging and primarily consists of systemic corticosteroids and a variety of immunosuppressants. Current treatment strategies are effective in most cases but hampered by the side effects of long-term immunosuppressive treatment. Intravenous immunoglobulin (IVIG) is one potential promising therapy for patients with autoimmune bullous skin diseases, and evidence of its effectiveness and safety is increasing. A number of autoimmune bullous skin diseases have been identified in which IVIG treatment may be beneficial. However, experience with IVIG in patients with autoimmune skin blistering disease is limited, where it is recommended for patients not responding to conventional therapy. The mode of action of IVIG in autoimmune diseases, including bullous diseases is far from being completely understood. We here summarize the clinical evidence supporting the notion, that IVIG is a promising therapeutic agent for the treatment of patients with autoimmune bullous skin disease. In addition, we review the proposed modes of action. In the future, randomized controlled trials are necessary to better determine the efficacy and adverse effects of IVIG in the treatment of autoimmune bullous skin diseases. In addition, insights into IVIG's mode of action might enable us to develop novel therapeutics to overcome the current shortage of IVIG.

Clinical applications of intravenous immunoglobulins (IVIg)--beyond immunodeficiencies and neurology

The clinical use of intravenous immunoglobulin (IVIg) has expanded beyond its traditional place in the treatment of patients with primary immunodeficiencies. Due to its multiple anti-inflammatory and immunomodulatory properties, IVIg is used successfully in a wide range of autoimmune and inflammatory conditions. Recognized autoimmune indications include idiopathic thrombocytopenic purpura (ITP), Kawasaki disease, Guillain-Barré syndrome and other autoimmune neuropathies, myasthenia gravis, dermatomyositis and several rare diseases. Several other indications are currently under investigation and require additional studies to establish firmly the benefit of IVIg treatment. Increasing attention is being turned to the use of IVIg in combination with other agents, such as immunosuppressive agents or monoclonal antibodies. For example, recent studies suggest that combination therapy with IVIg and rituximab (an anti-CD20 monoclonal antibody) may be effective for treatment of autoimmune mucocutaneous blistering diseases (AMBDs), with sustained clinical remission. The combination of IVIg and rituximab has also been used in the setting of organ transplantation. Firstly, IVIg +/- rituximab has been administered to highly human leucocyte antigen (HLA)-sensitized patients to reduce anti-HLA antibody levels, thereby allowing transplantation in these patients. Secondly, IVIg in combination with rituximab is effective in the treatment of antibody-mediated rejection following transplantation. Treatment with polyclonal IVIg is a promising adjunctive therapy for severe sepsis and septic shock, but its use remains controversial and further study is needed before it can be recommended routinely. This review covers new developments in these fields and highlights the broad range of potential therapeutic areas in which IVIg may have a clinical impact.

Analysis of thromboembolic risk related to high-dose intravenous immunoglobulin treatment: a preliminary clinical study of 10 patients with autoimmune mucocutaneous blistering diseases

BACKGROUND

Intravenous immunoglobulin (IVIg) treatment is a well-known treatment that has been used successfully in a broad spectrum of autoimmune diseases. Currently no data are available in the literature about the role of IVIg in the pathogenesis of thromboembolic events in patients with autoimmune blistering diseases refractory to conventional immunosuppressive treatment.

AIM

To determine the relationship between IVIg and thromboembolism in patients with autoimmune blistering diseases and to establish a protocol to deal with the thromboembolic risk.

METHODS

In our preliminary clinical study, 10 patients with autoimmune blistering diseases underwent IVIg cycles to a total of 133 cycles in all (total number of infusions in the patient group: 399), at a standard dose of 2 g/kg/infusion accompanied by an accurate and a complete clinical and laboratory screening for thromboembolism. Preventive measures, such as hydration before and after IVIg, and administration of 100 mg of acetyl salicylic acid (aspirin) or 1000 IU of subcutaneous heparin calcium per day for 3 weeks, were introduced to reduce the thromboembolic risk.

RESULTS

Throughout the 2 years of IVIg treatment, no patient developed a superficial and/or deep venous or arterial thrombosis, even though some of the patients had underlying thromboembolic risk factors and had tested positive for some congenital and acquired thrombophilia markers.

CONCLUSIONS

Our results indicate that thromboembolic events are uncommon, despite the presence of risk factors. However, as these disorders are very rare and the percentage of nonresponder patients is very low, further investigations are needed to better understand whether IVIg alone is able to trigger these fatal events in blistering disorders.

Treatment of juvenile pemphigus vulgaris with intravenous immunoglobulin therapy

We report the clinical response and follow-up on eight patients with juvenile pemphigus vulgaris treated with intravenous immunoglobulin. Six Caucasian females and two Caucasian males ages 15 to 18 (mean 15.5) were treated with intravenous immunoglobulin based on a published protocol. The indications were lack of response and development of serious side-effects to conventional therapy in four, lack of response to dapsone in two, and parental choice in two patients. In seven patients, a prolonged clinical remission was achieved. They received a mean of 28.5 cycles of intravenous immunoglobulin in a mean of 43.4 months and were followed for a mean of 29.8 months after discontinuing treatment. The remaining patient responded, but was lost to follow-up. Mean follow-up was 71.7 months. Six patients experienced mild headache, but no serious side-effects were observed in any patient. Intravenous immunoglobulin is a safe biological agent to use in the treatment of juvenile pemphigus vulgaris. It can be used as monotherapy and has the potential to induce and sustain long-term clinical remissions. In these eight patients, it appears that intravenous immunoglobulin is a safe biological agent without serious, immediate, or long-term side effects. Intravenous immunoglobulin is a valuable agent in the treatment of certain cases of juvenile pemphigus vulgaris.

Ocular manifestations of blistering diseases

Ocular manifestations are a comorbidity of a group of chronic autoimmune blistering diseases that includes mucous membrane pemphigoid, linear immunoglobulin A disease, epidermolysis bullosa acquisita, and ocular pemphigus vulgaris. Various diagnostic measures differentiate between the diseases and allow for appropriate treatment including a specific selection of immunomodulatory medications. New treatment modalities offer alternatives that may minimize disease severity and residual tissue damage and may reduce treatment-related complications.

Immunogenetic mechanisms for the coexistence of organ-specific and systemic autoimmune diseases

Background

Organ-specific autoimmune diseases affect particular targets in the body, whereas systemic diseases engage multiple organs. Both types of autoimmune diseases may coexist in the same patient, either sequentially or concurrently, sustained by the presence of autoantibodies directed against the corresponding autoantigens. Multiple factors, including those of immunological, genetic, endocrine and environmental origin, contribute to the above condition. Due to association of certain autoimmune disorders with HLA alleles, it has been intriguing to examine the immunogenetic basis for autoantigen presentation leading to the production of two or more autoantibodies, each distinctive of an organ-specific or systemic disease. This communication offers the explanation for shared autoimmunity as illustrated by organ-specific blistering diseases and the connective tissue disorders of systemic nature.

Presentation of the hypothesis

Several hypothetical mechanisms implicating HLA determinants, autoantigenic peptides, T cells, and B cells have been proposed to elucidate the process by which two autoimmune diseases are induced in the same individual. One of these scenarios, based on the assumption that the patient carries two disease-susceptible HLA genes, arises when a single T cell epitope of each autoantigen recognizes its HLA protein, leading to the generation of two types of autoreactive B cells, which produce autoantibodies. Another mechanism functioning whilst an epitope derived from either autoantigen binds each of the HLA determinants, resulting in the induction of both diseases by cross-presentation. Finally, two discrete epitopes originating from the same autoantigen may interact with each of the HLA specificities, eliciting the production of both types of autoantibodies.

Testing the hypothesis

Despite the lack of immediate or unequivocal experimental evidence supporting the present hypothesis, several approaches may secure a better understanding of shared autoimmunity. Among these are animal models expressing the transgenes of human disease-associated HLA determinants and T or B cell receptors, as well as in vitro binding studies employing purified HLA proteins, synthetic peptides, and cellular assays with antigen-presenting cells and patient's lymphocytes. Indisputably, a bioinformatics-based search for peptide motifs and the modeling of the conformation of bound autoantigenic peptides associated with their respective HLA alleles will reveal some of these important processes.

Implications of the hypothesis

The elucidation of HLA-restricted immune recognition mechanisms prompting the production of two or more disease-specific autoantibodies holds significant clinical ramifications and implications for the development of more effective treatment protocols.

The use of i.v. IG therapy in dermatology

The intravenous administration of exogenous pooled human immunoglobulin (i.v. IG) was originally licensed as antibody replacement therapy in patients with primary immunodeficiencies and there are currently six FDA-approved uses for this agent. Despite a current lack of FDA approval, off-label treatment of a multitude of dermatologic disorders with i.v. IG has shown exciting potential for this unique treatment modality. The diseases successfully treated with i.v. IG include autoimmune bullous diseases, connective tissue diseases, vasculitides, toxic epidermal necrolysis, and infectious disorders (such as streptococcal toxic shock syndrome). Currently the biggest drawback in the consideration of i.v. IG therapy in dermatologic disorders is the lack of randomized controlled trials. Nevertheless, there is a significant body of evidence demonstrating the efficacy of i.v. IG in patients with dermatologic disorders that are resistant to treatment with standard agents. In summary, i.v. IG constitutes a valuable and potentially life-saving agent in managing patients with a variety of dermatologic disorders under the appropriate circumstances.

Adjuvant high-dose intravenous immunoglobulin therapy can be easily and safely introduced as an alternative treatment in patients with severe pemphigus vulgaris: a retrospective preliminary study

BACKGROUND

Long-term corticosteroid therapy, often in association with other immunosuppressive agents, is considered the mainstay of pemphigus vulgaris (PV) therapy. Recent evidence has been changing this paradigm as patients who are non-responsive to conventional therapies or who experience severe adverse effects have been successfully treated with high-dose intravenous immunoglobulin (IVIg). However, the shift from conventional therapies to IVIg represents a major challenge in the daily practice of non-experienced clinicians because of potential adverse effects and other issues relevant to IVIg therapy such as the necessity for premedication, selection of cases, modality of infusion, patient monitoring, and the cost and length of hospital stay.

OBJECTIVE

The purpose of this preliminary study was to evaluate and report outcomes of treatment with IVIg in eight selected PV patients meeting clearly defined criteria for initiation of this therapy.

METHODS

Available guidelines for IVIg therapy in patients with autoimmune mucocutaneous blistering diseases were followed. Clinical response, induction and duration of remission, strategies for prevention of adverse effects, and total days of hospital stay in eight patients with severe PV treated with IVIg were retrospectively evaluated.

RESULTS

All patients had an effective clinical response without adverse reactions, leading to a significant corticosteroid-sparing effect.

CONCLUSION

Our results indicate that, when current guidelines are followed, IVIg therapy can be easily and safely introduced as a treatment alternative in patients with severe PV. Careful monitoring of patients, utilization of a multidisciplinary approach, and evaluation of hospital-related issues can help the non-experienced clinician successfully manage patients with severe PV requiring IVIg therapy.

Cicatricial pemphigoid with severe gingival and laryngeal involvement in an 18-year-old female

Cicatricial pemphigoid (CP), also known as mucous membrane pemphigoid, is an autoimmune vesiculobullous disease occurring mostly in elderly people and seldom occurring in individuals under the age of 20 years. It predominantly affects the mucosal surfaces, primarily the oral and conjunctival mucosa. Uncommonly, the upper aerodigestive tract is involved, which can lead to life-threatening complications. We present the case of an 18-year-old girl with desquamative gingivitis and severe laryngeal webbing and stenosis, caused by cicatricial pemphigoid. Airway management necessitated a tracheostomy and additional surgical procedure. The clinical, diagnostic, and therapeutic features of this disease are discussed, focusing on the oral and unique laryngeal manifestations.

Variations in serum hemoglobin, albumin, and electrolytes in patients receiving intravenous immunoglobulin therapy: a real clinical threat?

BACKGROUND AND OBJECTIVE

Intravenous immunoglobulin (IVIg) is a solution of globulins containing antibodies derived from pooled human plasma of donors and used in the treatment of a number of immune deficiencies and autoimmune diseases. However, several investigators have reported biochemical alterations with use of IVIg. The objective of this study was to evaluate the effects of IVIg therapy on selected biochemical and hematologic parameters in patients with autoimmune mucocutaneous blistering diseases (AMBDs).

METHODS

In this preliminary clinical study, ten patients with AMBDs (seven with pemphigus vulgaris and three with mucous membrane pemphigoid) received 133 cycles of IVIg for a total of 399 infusions. We evaluated the effects of IVIg therapy on serum hemoglobin (Hb), albumin, and electrolyte levels, including sodium (Na+), potassium (K+), chloride (Cl-) and calcium (Ca2+). Values of these parameters were measured 24 hours before, during, and 24 hours and 4 weeks after the 3-day infusion period.

RESULTS

The observed variations in serum electrolyte levels were physiologically and clinically negligible. Furthermore, 24 hours after the last infusion, mean electrolyte values had spontaneously returned to normal levels without the need for additional supplementation: Na+ 137.59+/-1.42 mmol/L (p=0.6091 vs baseline); K+ 3.97+/-0.5 mmol/L (p=0.2689); Cl- 103.4+/-2.69 mmol/L (p=0.0388); and Ca2+ 9.07+/-0.44 mg/dL (p=0.5332). Conversely, significant variations in mean Hb and albumin levels were observed. When measured 24 hours after the last infusion, mild/moderate decreases in Hb (11.62+/-2.12 g/dL; p=0.009 vs baseline) and/or albumin (mean 3.14+/-0.24 g/dL; p=0.0016 vs baseline) were evident. Such changes may, albeit very rarely, be of sufficient clinical significance in individual patients as to necessitate additional treatment.

CONCLUSION

In patients receiving intravenous IVIg for AMBDs, electrolyte values should be monitored but do not represent a real clinical threat. Hemoglobin and albumin values may be altered sufficiently to require additional treatment but this is a very rare occurrence. These findings confirm and extend previous reports of the safety of IVIg therapy.

Induction of immune tolerance by oral IVIG

In the last years evidence has been provided for the importance of B cells in the pathogenesis of rheumatoid arthritis (RA). Several studies have supported the concept that humoral immunity, manifested by the production of autoantibodies, such as rheumatoid factors (RFs), plays a significant role in the course of the disease. Specific targeting of autoantibody-producing B cells, such as RF-producing B cells, should therefore be a promising new approach in the treatment of RA. We used a mouse model to induce human RF responses and asked the question whether oral treatment with the antigen (human IgG) recognized by RFs could induce immune tolerance to RF responses. Balb/c mice were orally treated with polyvalent human IgG before and after immunization with insoluble immune complexes (ICs) that triggered the induction of RFs. Serum titers of RFs were significantly reduced after both primary and booster immunization when human IgG was given as a single oral dose or continuously in drinking water. Continuous treatment with human IgG even prevented booster effects on RFs when treatment started after primary immunization. Treatment with IgG fragments provided evidence that the observed effect of human IgG was mediated by the Fc part and not the Fab part of IgG. Furthermore, transfer of spleen cells obtained from mice after oral treatment with human IgG suppressed RF responses in recipient mice. These data give promising indications that oral human IgG might represent an alternative approach for immunosuppressive B-cell targeted therapies in RA.