French recommendations for the management of systemic sclerosis

Systemic sclerosis (SSc) is a generalized disease of the connective tissue, arterioles, and microvessels, characterized by the appearance of fibrosis and vascular obliteration. There are two main phenotypical forms of SSc: a diffuse cutaneous form that extends towards the proximal region of the limbs and/or torso, and a limited cutaneous form where the cutaneous sclerosis only affects the extremities of the limbs (without passing beyond the elbows and knees). There also exists in less than 10% of cases forms that never involve the skin. This is called SSc sine scleroderma. The prognosis depends essentially on the occurrence of visceral damage and more particularly interstitial lung disease (which is sometimes severe), pulmonary arterial hypertension, or primary cardiac damage, which represent the three commonest causes of mortality in SSc. Another type of involvement with poor prognosis, scleroderma renal crisis, is rare (less than 5% of cases). Cutaneous extension is also an important parameter, with the diffuse cutaneous forms having less favorable prognosis.

[Impact of disease on daily activities, emotions and quality of life of patients with hereditary angioedema]

INTRODUCTION

Hereditary angioedema (HAE) is characterized by recurrent attacks of swelling of various locations and severity. An impaired quality of life of patients with HAE has been reported by several studies. We aimed at examining the overall impact of the disease in patients followed for type I HAE, particularly its impact on daily life activities, emotions and quality of life.

METHODS

A questionnaire was distributed to patients consulting for type I HAE, collecting demographics, disease characteristics, impact on professional life, Hospital Anxiety and Depression score (HAD), SF-36 score and the McMaster Toronto Arthritis Patient Preference Disability Questionnaire (MACTAR).

RESULTS

The 33 patients included reported an average of 5.17 attacks over the last year. Stress was the main trigger A long-term treatment was reported by 58% of patients, 72% received specific treatment in the event of a serious attack. Sick days were reported by 33% of patients during their studies, and by 34% during work. One patient suffered from depressive symptoms and ten from anxious symptoms, according to the HAD score. The areas most impacted on the SF-36 score were general health and vitality. The mean score for MACTAR was low.

CONCLUSION

HAE still has a significant impact on the daily and emotional lives of patients, despite the availability of prophylactic and crisis treatments.

Quantification of Antifibrillarin (anti-U3 RNP) Antibodies: A New Insight for Patients with Systemic Sclerosis

Background: The detection of additional autoantibodies is of great concern in systemic sclerosis (SSc) when those included in the ACR/EULAR classification are negative. In this context, the interest of antifibrillarin (anti-U3RNP) autoantibodies (AFAs) in the routine evaluation of SSc remains unclear. We aimed to assess the relevance of AFAs and their clinical association in SSc patients. Methods: In a multicenter observational retrospective study, we collected immunological and clinical data associated with AFA positivity in SSc (n = 42) and non-SSc patients (n = 13). Patients with SSc negative for AFAs (n = 83) were considered as a control group. AFAs were detected by indirect immunofluorescence (IIF) using HEp-2 cells, EliA or immunoblot techniques. Results: We confirmed a typical nuclear IIF pattern and showed that AFAs are mostly exclusive towards SSc conventional autoantibodies. Although also observed in non-SSc patients, high levels of AFAs with the ELiA technique allowed the diagnosis of SSc. Compared to AFA-negative SSc patients, AFA-positive SSc patients more frequently exhibited visceral involvements. They more frequently suffered from the diffuse cutaneous form and had a higher global severity of the disease. Conclusions: We demonstrate the usefulness of quantifying AFAs in the immunological exploration of SSc, especially when patients are seronegative for SSc conventional autoantibodies and display a typical IIF pattern. AFAs might constitute an interesting marker of SSc severity.

Activités de recours et de recherche d’un service de Médecine Interne : une place pour la télémédecine, au-delà de la pandémie COVID-19 ?

Introduction

Les services de Médecine Interne mènent une importante activité de recours expert et de recherche, grevée par plusieurs obstacles. L’activité d’avis spécialisés est chronophage, non valorisée, et limitée par l’impossibilité d’échanger simplement les éléments du dossier médical. L’activité de recherche clinique est limitée par la fréquence des visites protocolaires. L’objectif de ce travail est de déterminer si la télémédecine (TLM) peut contribuer à résoudre ces difficultés.

Patients et méthodes

Concernant l’activité de recours, nous avons demandé aux médecins de déclarer les avis donnés à l’aide d’un formulaire standardisé, afin de déterminer s’ils validaient les critères de téléconsultation (TLC) ou de télé-expertise (TLE). Concernant l’activité de recherche, nous avons remis aux investigateurs et à 50 patients un questionnaire sur l’acceptabilité de TLC protocolaires.

Résultats

Concernant l’activité de recours, on dénombrait 120 avis (soit 21 h) hebdomadaires, dont 29 % aux patients et 69 % à des médecins. Soixante et un pour cent des avis aux patients validaient les critères de TLC ; 18 % des avis aux médecins ceux de TLE. Concernant l’activité de recherche, 70 % des investigateurs considéraient la fréquence des visites comme limitant les inclusions ; près de la moitié des patients serait favorable au recours à des TLC à la place (40 %) ou en plus (56 %) des visites présentielles. En termes de facturation, la TLM représente un revenu potentiel de 300 € hebdomadaires pour le TLE et 616€ hebdomadaires pour le TLC.

Conclusion

Si le recours à la TLM comme procédure dégradée au présentiel s’est démocratisé avec la pandémie, les solutions qu’elle apporte aux difficultés rencontrées dans les activités d’avis et de recherche peuvent contribuer à intégrer pleinement son usage dans le suivi standard des patients. Si tel était le cas, on pourrait tout à fait imaginer avec ce budget (47 632 €/an) pouvoir financer un praticien hospitalier supplémentaire à temps partiel.

AB0401 CAN DUAL-ENERGY CT LUNG PERFUSION DETECT ABNORMALITIES AT THE LEVEL OF LUNG CIRCULATION IN SYSTEMIC SCLEROSIS (SSC)? PRELIMINARY EXPERIENCE IN 101 PATIENTS

Background:

Systemic sclerosis (SSc) is an autoimmune disorder that is characterized by a interplay of vascular abnormalities, immune system activation and an uncontrolled fibrotic response associated with interstitial lung disease affecting about 40% of patients. Identification of ILD relies on high-resolution CT that identify features suggestive of the histologic patterns of SSc(1). CT is used to determine pattern and extent of ILD and participates in the prediction of ILD progression(2).

All group of pulmonary hypertension (PH) may occur with an overall prevalence reported in up to one fifth of patient. Whereas extensive SSc-ILD can be responsible for PH, PH can also be seen as a consequence of myocardial abnormalities or as primarily affecting small pulmonary arteries and classified as pulmonary arterial hypertension.

Dual-energy CT introduction offers perspectives in the evaluation of SSc-related pulmonary manifestations. While these are not strictly perfusion images, they have been reported as adequate surrogate markers of lung perfusion (3). In the field of PH, detection of perfusion defects highly concordant with V/Q scintigraphic findings has been reported in the diagnostic approach of CTEPH but also in the differential diagnosis between PAH and peripheral forms of CTEPH (4).

Objectives:

To investigate lung perfusion abnormalities in patients with SSc.

Methods:

The study population included 101 patients who underwent dual-energy CT (DECT) angiography in the follow-up of SSc. CT examinations were obtained on a 3rd-generation dual-source CT system with reconstruction of morphologic and perfusion images. All patients underwent pulmonary function tests within two months of the follow-up CT scan. Fifteen patients had right heart catheterization-proven PH.

Results:

Our population included patients without SSc lung involvement (Group 1; n=37), patients with SSc-related ILD (Group 2; n=56) of variable extent (Group 2a: ≤10%: n=17; Group 2b: between 11-50%: n=31; Group 2c: >50%: n=8) and patients with PVOD/PCH (Group 3; n=8). Lung perfusion was abnormal in 8 patients in G 1 (21.6%), 14 patients in G 2 (25%) and 7 patients in G 3 (87.5%). Perfusion changes were mainly composed of bilateral perfusion defects, including patchy, PE-type perfusion defects and areas of hypoperfusion of variable size. In G 1 and G 2a (n=54): (a) patients with abnormal lung perfusion (n=14) had a significantly higher proportion of NYHA III/IV scores of dyspnea (p=0.031), a shorter mean walking distance at the 6MWT (p=0.042) and a trend towards lower mean DLCO% (p=0.055) when compared to patients with normal lung perfusion (n=40); (b) a negative albeit weak correlation was found between the iodine concentration in both lungs and the DLCO% (r=-0.27; p=0.059) whereas no correlation was found with PAPs (r=0.16; p=0.29) and walking distance during the 6MWT (r=-0.029; p=0.84).

Conclusion:

DECT lung perfusion provides complementary information to HRCT scans, depicting perfusion changes in SSc patients with normal or minimally infiltrated lung parenchyma.

References:

[1]Kim EA, Lee KS, Johkoh T, Kim TS, Suh GY, Kwon OJ, et al. Interstitial lung diseases associated with collagen vascular diseases: radiologic and histopathologic findings. Radiogr Rev Publ Radiol Soc N Am Inc. 2002 Oct;22 Spec No:S151-165.

[2]Goh NSL, Desai SR, Veeraraghavan S, Hansell DM, Copley SJ, Maher TM, et al. Interstitial lung disease in systemic sclerosis: a simple staging system. Am J Respir Crit Care Med. 2008 Jun 1;177(11):1248–54.

[3]Fuld MK, Halaweish AF, Haynes SE, Divekar AA, Guo J, Hoffman EA. Pulmonary perfused blood volume with dual-energy CT as surrogate for pulmonary perfusion assessed with dynamic multidetector CT. Radiology. 2013 Jun;267(3):747–56.

[4]Giordano J, Khung S, Duhamel A, Hossein-Foucher C, Bellèvre D, Lamblin N, et al. Lung perfusion characteristics in pulmonary arterial hypertension and peripheral forms of chronic thromboembolic pulmonary hypertension: Dual-energy CT experience in 31 patients. Eur Radiol. 2017 Apr;27(4):1631–9.

Disclosure of Interests:

None declared

POS1454-HPR AESTHETIC IMPAIRMENT IN PATIENTS WITH SYSTEMIC SCLEROSIS: A CASE CONTROL STUDY USING A SEMI-QUANTITATIVE SCALE FOR BODY IMAGE ASSESSMENT

Background:

Systemic sclerosis (SSc) is a fibrotic autoimmune disease characterized by dermatological involvement. Skin involvement can alter appearance, which can have a psychological impact(1). Assessment of body image could be central in optimizing care. Yet, data are scarce(2).

Objectives:

The main objective of our study was to assess aesthetic impairment measured on a visual aesthetic scale (AES) (3) in patients with SSc compared to a group of healthy subjects. Secondary objectives were to assess associations between aesthetic impairment and standardized questionnaires for aesthetic impairment as well as clinical, biological, psychological/quality of life, and functional parameters of SSc.

Methods:

The “Sclero-esthet” study is a descriptive single-center study of two populations: patients with SSc, included in a referral center for systemic and autoimmune diseases at Lille Hospital, France, and healthy controls.

Results:

This study, from January 2017 to October 2017, included 88 patients (69 [78.4%] women) with a median age of 52 years (range: 43 to 59) and 88 controls (49 [55.7%] women) with a median age of 45 years (range: 32 to 55). Perception of physical changes assessed using the AES was greater in cases than in controls (3.7 ± 0.3 vs 2.8 ± 0.3, p=0.028), with statistical correlation with ASWAP. SSc patients with anxiety or depressive symptoms had significantly higher AES scores. Cases presented poorer quality of life than controls.

Conclusion:

The AES appears to be a good tool to evaluate aesthetic impairment. Correlations found with psychological and quality of life parameters support the need to improve patient management in this field.

References:

[1]Cash TF. Body image: past, present, and future. Body Image 2004;1(1):1–5.

[2]Benrud-Larson LM, Heinberg LJ, Boling C, Reed J, White B, Wigley FM. Body image dissatisfaction among women with scleroderma: extent and relationship to psychosocial function. Health Psychol mars. 2003;22(2):130–9.

[3]Nguyen C, Ranque B, Baubet T, Bérezné A, Mestre-Stanislas C, Rannou F, et al. Clinical, Functional and Health-Related Quality of Life Correlates of Clinically Significant Symptoms of Anxiety and Depression in Patients with Systemic Sclerosis: A Cross-Sectional Survey. PLoS ONE 2014;9(2).

[4]Heinberg LJ, Kudel I, White B, Kwan A, Medley K, Wigley F. Assessing body image in patients with systemic sclerosis (scleroderma): Validation of the Adapted Satisfaction with Appearance Scale. Body Image 2007;4(1):79–86.

Disclosure of Interests:

None declared

Fatal Enterovirus-related Myocarditis in a Patient with Devic's Syndrome Treated with Rituximab

Enteroviruses are a frequent source of infection and among the most common central nervous system viral pathogens. Enteroviruses – in particular, the Coxsackie B viruses – are a known cause of myocarditis. Rituximab is a genetically engineered chimeric anti-CD20 monoclonal antibody. Many reports in the literature suggest a higher risk of infection following repeated rituximab therapy, including viral infection. However, observations of enterovirus-related myocarditis in the context of rituximab treatment are scarce. The authors describe the case of a patient with neuromyelitis optica spectrum disorder who developed severe and fatal enterovirus-related myocarditis after rituximab therapy with a difficult differential diagnosis of autoimmune or giant-cell myocarditis. This case highlights the importance of complete diagnostic workup in difficult cases of myocarditis, including endomyocardial biopsies.

Serious Infectious Events and Immunoglobulin Replacement Therapy in Patients With Autoimmune Disease Receiving Rituximab: A Retrospective Cohort Study

BACKGROUND

Rituximab (RTX) is widely administered to patients with autoimmune disease (AID). This study aimed to estimate the incidence of serious infectious events (SIEs) after RTX initiation in patients with AID. We also described the characteristics and risk factors of SIEs, and immunoglobulin replacement therapy (IgRT) strategies.

METHODS

Patients treated between 2005 and 2016 were included in this retrospective monocentric cohort study. An RTX course was defined as the complete RTX treatment regimen received by a given patient for AID. SIEs and IgRT were right-censored at 24 months after RTX initiation.

RESULTS

Two hundred twenty-one patients were included (corresponding to 276 RTX courses). Reasons for RTX initiation included connective tissue disease (38%), systemic vasculitis (36%), and autoimmune cytopenia (22%). The 1- and 2-year incidences of SIEs were 17.3 (95% confidence interval [CI], 12.0-22.5) and 11.3 (95% CI, 8.1-14.5) per 100 person-years, respectively. Forty-seven SIEs were observed, mostly comprising pneumonias (45%) and bacteremias (21%). When documented, the microorganisms were bacterial (55%) and fungal (12%). Identified risk factors of SIEs were age, history of diabetes, history of cancer, concomitant steroid treatment, and low CD4 lymphocyte count at RTX initiation. IgRT was started in 22 RTX courses (8%).

CONCLUSIONS

In patients with AID treated with RTX, the 1- and 2-year incidence of SIE was 17.3 and 11.3 per 100 person-years, respectively. Reports of SIE characteristics, risk factors, and IgRT strategies highlight the need for an appropriate and individualized assessment prior to and following RTX to prevent SIEs, particularly in patients with comorbidities.

Competitive binding of STATs to receptor phospho-Tyr motifs accounts for altered cytokine responses

Cytokines elicit pleiotropic and non-redundant activities despite strong overlap in their usage of receptors, JAKs and STATs molecules. We use IL-6 and IL-27 to ask how two cytokines activating the same signaling pathway have different biological roles. We found that IL-27 induces more sustained STAT1 phosphorylation than IL-6, with the two cytokines inducing comparable levels of STAT3 phosphorylation. Mathematical and statistical modeling of IL-6 and IL-27 signaling identified STAT3 binding to GP130, and STAT1 binding to IL-27Rα, as the main dynamical processes contributing to sustained pSTAT1 levels by IL-27. Mutation of Tyr613 on IL-27Rα decreased IL-27-induced STAT1 phosphorylation by 80% but had limited effect on STAT3 phosphorgylation. Strong receptor/STAT coupling by IL-27 initiated a unique gene expression program, which required sustained STAT1 phosphorylation and IRF1 expression and was enriched in classical Interferon Stimulated Genes. Interestingly, the STAT/receptor coupling exhibited by IL-6/IL-27 was altered in patients with systemic lupus erythematosus (SLE). IL-6/IL-27 induced a more potent STAT1 activation in SLE patients than in healthy controls, which correlated with higher STAT1 expression in these patients. Partial inhibition of JAK activation by sub-saturating doses of Tofacitinib specifically lowered the levels of STAT1 activation by IL-6. Our data show that receptor and STATs concentrations critically contribute to shape cytokine responses and generate functional pleiotropy in health and disease.

Clinical phenotypes of extrapulmonary sarcoidosis: an analysis of a French, multi-ethnic, multicentre cohort

Sarcoidosis is a rare disease of unknown cause with wide heterogeneity in clinical features and outcomes. We aimed to explore sarcoidosis phenotypes and their clinical relevance with particular attention to extrapulmonary subgroups.The Epidemiology of Sarcoidosis (EpiSarc) study is a French retrospective multicentre study. Sarcoidosis patients were identified through national hospitalisation records using appropriate codes from 11 hospital centres between 2013 and 2016 according to a standardised protocol. Medical charts were reviewed. The phenotypes of sarcoidosis were defined using a hierarchical cluster analysis.A total of 1237 patients were included (562 men and 675 women). The mean age at sarcoidosis diagnosis was 43.5±13 years. Hierarchical cluster analysis identified five distinct phenotypes according to organ involvement and disease type and symptoms: 1) erythema nodosum, joint involvement and hilar lymph nodes (n=180); 2) eye, neurological, digestive and kidney involvement (n=137); 3) pulmonary involvement with fibrosis and heart involvement (n=630); 4) lupus pernio and a high percentage of severe involvement (n=41); and 5) hepatosplenic, peripheral lymph node and bone involvement (n=249). Phenotype 1 was associated with being European/Caucasian and female and with non-manual work, phenotype 2 with being European/Caucasian, and phenotypes 3 and 5 with being non-European/Caucasian. The labour worker proportion was significantly lower in phenotype 5 than in the other phenotypes.This multicentre study confirms the existence of distinct phenotypes of sarcoidosis, with a non-random distribution of organ involvement. These phenotypes differ according to sex, geographical origin and socioprofessional category.

18F-FDG positron emission tomography scanning in systemic sclerosis-associated interstitial lung disease: a pilot study

Background

Interstitial lung disease is a common complication of systemic sclerosis (SSc-ILD), and it remains difficult to accurately predict its course. Progressing ILD could be more metabolically active, suggesting that the ¹⁸F-FDG tracer could be a tool in the managing of SSc-ILD.

Methods

In our center, SSc patients and controls (non-Hodgkin lymphoma cured after first-line regimen) who had received a PET/CT were screened retrospectively. The FDG uptake (visual intensity, pattern, SUV_max) was systematically recorded in > 30 regions of interest (ROIs) linked to SSc in a blind reviewing by 2 independent nuclear medicine physicians using a standardized form.

Results

Among the 545 SSc patients followed up in our center, 36, including 22 SSc-ILDs, had a PET/CT, whose indication was cancer screening in most cases. The mean ± SD age was 57.9 ± 13.0 years with 20/36 females. Fourteen patients had a disease duration of less than 2 years. A third had anti-centromere antibodies and 27.8% had anti-topoisomerase antibodies. Pulmonary FDG uptakes were higher in SSc patients than in controls (n = 89), especially in those with ILD compared with those without ILD. Pulmonary FDG uptakes were positively correlated with the ILD severity (fibrosis extent, %FVC, and %D_LCO). No significant difference was found in the FDG uptakes from extrathoracic ROIs. Progressing SSc-ILDs within the 2 years after PET/CT (n = 9) had significant higher pulmonary FDG uptakes at baseline than stable SSc-ILDs (n = 13).

Conclusion

PET/CT could be a useful tool in the assessment of the severity and the prediction of pulmonary function outcome of SSc-ILD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02460-8.

Hemodynamic Response to Treatment and Outcomes in Pulmonary Hypertension Associated With Interstitial Lung Disease Versus Pulmonary Arterial Hypertension in Systemic Sclerosis: Data From a Study Identifying Prognostic Factors in Pulmonary Hypertension Associated With Interstitial Lung Disease

OBJECTIVE

Patients with systemic sclerosis and both pulmonary hypertension and interstitial lung disease (SSc-PH-ILD) generally carry a worse prognosis than patients with SSc and pulmonary arterial hypertension (SSc-PAH) without ILD. There is no evidence of the efficacy of PAH therapies in SSc-PH-ILD. We undertook this study to compare survival of and response to treatment in patients with SSc-PH-ILD and those with SSc-PAH.

METHODS

We analyzed 128 patients (66 with SSc-PH-ILD and 62 with SSc-PAH) from 15 centers, in whom PH was diagnosed by right-sided heart catheterization; they were prospectively included in the PH registry. All patients received PAH-specific therapy. Computed tomography of the chest was used to confirm or exclude ILD.

RESULTS

At baseline, patients with SSc-PH-ILD had less severe hemodynamic impairment than those with SSc-PAH (pulmonary vascular resistance 5.7 Wood units versus 8.7 Wood units; P = 0.0005) and lower diffusing capacity for carbon monoxide (median 25% [interquartile range (IQR) 18%, 35%] versus 40% [IQR 31%, 51%]; P = 0.0005). Additionally, patients with SSc-PH-ILD had increased mortality (8.1% at 1 year, 21.2% at 2 years, and 41.5% at 3 years) compared to those with SSc-PAH (4.1%, 8.7%, and 21.4%, respectively; P = 0.04). Upon treatment with PAH-targeted therapy, no improvement in the 6-minute walk distance was observed in either group. Improvement in the World Health Organization functional class was observed less frequently in patients with SSc-ILD-PH compared to those with SSc-PAH (13.6% versus 33.3%; P = 0.02). Hemodynamics improved similarly in both groups.

CONCLUSION

ILD confers a worse prognosis to SSc-PH. Response to PAH-specific therapy is clinically poor in SSc-PH-ILD but was not found to be hemodynamically different from the response observed in SSc-PAH.

Severe SARS-CoV-2 patients develop a higher specific T-cell response

OBJECTIVES

Assessment of the adaptive immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is crucial for studying long-term immunity and vaccine strategies. We quantified IFNγ-secreting T cells reactive against the main viral SARS-CoV-2 antigens using a standardised enzyme-linked immunospot assay (ELISpot).

METHODS

Overlapping peptide pools built from the sequences of M, N and S viral proteins and a mix (MNS) were used as antigens. Using IFNγ T-CoV-Spot assay, we assessed T-cell and antibody responses in mild, moderate and severe SARS-CoV-2 patients and in control samples collected before the outbreak.

RESULTS

Specific T cells were assessed in 60 consecutive patients (mild, n = 26; moderate, n = 10; and severe patients, n = 24) during their follow-up (median time from symptom onset [interquartile range]: 36 days [28;53]). T cells against M, N and S peptide pools were detected in n = 60 (100%), n = 56 (93.3%), n = 55 patients (91.7%), respectively. Using the MNS mix, IFNγ T-CoV-Spot assay showed a specificity of 96.7% (95% CI, 88.5-99.6%) and a specificity of 90.3% (75.2-98.0%). The frequency of reactive T cells observed with M, S and MNS mix pools correlated with severity and with levels of anti-S1 and anti-RBD serum antibodies.

CONCLUSION

IFNγ T-CoV-Spot assay is a reliable method to explore specific T cells in large cohorts of patients. This test may become a useful tool to assess the long-lived memory T-cell response after vaccination. Our study demonstrates that SARS-CoV-2 patients developing a severe disease achieve a higher adaptive immune response.

Acquired Hemophilia A in IgG4-Related Disease: Case Report, Immunopathogenic Study, and Review of the Literature

We report the observation of a 75-year-old patient referred for cervical lymphadenopathies. A pre-lymphadenectomy blood work revealed an asymptomatic elevation of aPTT with low factor VIII (FVIII) levels and high anti-FVIII antibodies titers, consistent with acquired hemophilia A (AHA). Histological work-up of a cervical lymphadenopathy revealed benign follicular hyperplasia with IgG4⁺ lymphoplasmacytic infiltration; and serum IgG4 levels were markedly elevated, compatible with IgG4-related disease (IgG4-RD). He was successfully treated with a 9-month course of prednisone, secondarily associated with rituximab when an AHA relapse occurred. As this patient presented with an unusual association of rare diseases, we wondered whether there was a link between the two conditions. Our first hypothesis was that the anti-FVIII autoantibodies could be directly produced by the proliferating IgG4⁺ plasma cells as a result of broken tolerance to autologous FVIII. To test this assumption, we determined the anti-FVIII IgG subclasses in our patient and in a control group of 11 AHA patients without IgG4-RD. The FVIII inhibitor was mostly IgG4, with an anti-FVIII IgG4/IgG1 ratio of 42 at diagnosis and 268 at relapse in our patient; similar values were observed in non-IgG4-RD AHA patients. As a second hypothesis, we considered whether the anti-FVIII activity could be the result of a non-specific autoantibody production due to polyclonal IgG4⁺ plasma cell proliferation. To test this hypothesis, we measured the anti-FVIII IgG4/total IgG4 ratio in our patient, as well as in several control groups: 11 AHA patients without IgG4-RD, 8 IgG4-RD patients without AHA, and 11 healthy controls. We found that the median [min-max] ratio was higher in AHA-only controls (2.4 10^-2 [5.7 10^-4-1.79 10^-1]), an oligoclonal setting in which only anti-FVIII plasma cells proliferate, than in IgG4-RD-only controls (3.0 10^-5 [2.0 10^-5-6.0 10^-5]), a polyclonal setting in which all IgG4⁺ plasma cells proliferate equally. Our patient had intermediate ratio values (2.7 10^-3 at diagnosis and 1.0 10^-3 at relapse), which could plead for a combination of both mechanisms. Although no definitive conclusion can be drawn, we hypothesized that the anti-FVIII autoantibody production in our IgG4-RD AHA patient could be the result of both broken tolerance to FVIII and bystander polyclonal IgG4⁺ plasma cell proliferation.