Overexpression of IgG2 in patients resembling IgG4-related disease with normal IgG4.

IgG4-Related Disease (IgG4-RD) results from tissue infiltration by IgG4-expressing plasma cells and lymphocytes, leading to fibrosis and organomegaly. Clinical presentation is remarkably variable according to organ involvement, and high IgG4 serum concentration, initially considered a diagnostic hallmark of IgG4-RD, tends to be forgone as an indispensable criterion for its diagnosis; it can indeed be absent in some patients, highlighting the diversity of presentation of this dysimmune condition. Nevertheless, elevation of IgG4 serum concentration in suggestive settings remains an argument in favour of IgG4-RD, and while other IgG subclasses can be elevated, this biological feature lacks any diagnostic value. We retrospectively studied 9 patients (5 females, 4 males, 31-81 years old) for whom a diagnosis of IgG4-RD had been considered, based on clinical, imaging or histological criteria, but appeared to display abnormally high serum IgG2 while IgG4 levels were normal. Increased serum IgG1 in one case and increased IgG3 in another one were also noticed. Immunohistochemical analyses of intracellular immunoglobulins could be performed on tissue lymph node biopsies from 2 patients, which demonstrated strong infiltration with IgG2-expressing plasma cells. Thus, overexpression of IgG2 subclass may highlight cases of dysimmune disorders resembling IgG4-RD, although the disease trigger might be different, notably infectious. We suggest measuring all serum IgG subclass levels in patients with features consistent with IgG4-RD.

IgG4-related disease in patients with idiopathic orbital inflammation syndrome: data from the French SIOI prospective cohort.

PURPOSE: To better characterize IgG4-related disease (RD) in the setting of idiopathic orbital inflammation syndrome (IOIS). METHODS: National, multicentre, prospective, observational cohort study. Among the patients consecutively included in the French multicentre SIOI cohort, we selected those who underwent orbital and/or adnexal biopsy. Clinical, morphological and pathological findings at diagnosis were blindly analysed. Serum IgG4 levels at inclusion were measured and all available biopsy specimens were immunostained for IgG4 and IgG. Biopsy samples with more than 10 IgG4-positive plasma cells per high-power field and a IgG4+/IgG+ plasma cell ratio above 40% were scored as positive. IgG4-positive patients were then screened for comprehensive diagnostic criteria for IgG4-RD. RESULTS: Of the 87 patients included, 35 had histologically documented IOIS. Thirteen patients (37%) with a mean age at onset of 27 years (range 21-78) had IgG4-positive biopsies, among which 10 patients (77%) and 3 (23%, with IgG4 serum levels >1.35 g/L) were considered as having probable and definite IgG4-RD, respectively. The latter 13 patients more frequently fulfilled histological criteria for IgG4-RD (including plasmacytic infiltrate (p = 0.006), fibrosis (p = 0.0025) and periphlebitis (p = 0.075)) than IgG4-negative patients. Storiform fibrosis was exclusively found in orbital tissues from IgG4-positive patients (n = 3, 23%). Eosinophilia associated with recurrent sinusitis or asthma was a prominent feature in patients with definite IgG4-RD. CONCLUSIONS: More than one-third of patients with biopsy-proven IOIS satisfied criteria for IgG4-RD, but only a few had a definite type.

Subclasses of Monoclonal (Type I) Immunoglobulin G Cryoglobulins: Report on Two Distinct Cases with Myeloma.

BACKGROUND: While different clinical manifestations of IgM and IgG monoclonal cryoglobulins have been demonstrated, little is known about the roles of IgG subclasses in the pathophysiology of these conditions. METHODS: In two cases of myeloma-associated monoclonal (type I) cryoglobulinemia with quite distinct clinical and biological features, serum samples were analyzed using an original IgG subclass-specific immunoblotting technique. RESULTS: The first case had painful arthritis of hands and feet, with skin purpura and a sharp decrease of complement C4 level, and the cryoglobulin was of IgG1 subclass. The second case displayed mostly thrombotic lesions of the limb extremities, C3 and C4 serum levels were normal, and the cryoglobulin belonged to the IgG2 subclass. CONCLUSIONS: Type I cryoglobulins of distinct IgG subclasses may result in different syndromes. In both cases, the treatment relies on eradication of the underlying plasma cell dyscrasia.

Pregnancy allows the transfer and differentiation of fetal lymphoid progenitors into functional T and B cells in mothers.

T lymphocytes of fetal origin found in maternal circulation after gestation have been reported as a possible cause for autoimmune diseases. During gestation, mothers acquire CD34+CD38+ cells of fetal origin that persist decades. In this study, we asked whether fetal T and B cells could develop from these progenitors in the maternal thymus and bone marrow during and after gestation. RAG-/--deficient female mice (Ly5.2) were mated to congenic wild-type Ly5.1 mice (RAG+/+). Fetal double-positive T cells (CD4+CD8+) with characteristic TCR and IL-7R expression patterns could be recovered in maternal thymus during the resulting pregnancies. We made similar observations in the thymus of immunocompetent mothers. Such phenomenon was observed overall in 12 of 68 tested mice compared with 0 of 51 controls (p=0.001). T cells could also be found in maternal spleen and produced IFN-gamma in the presence of an allogenic or an Ag-specific stimulus. Similarly, CD19+IgM+ fetal B cells as well as plasma Igs could be found in maternal RAG-/- bone marrow and spleen after similar matings. Our results suggest that during gestation mothers acquire fetal lymphoid progenitors that develop into functional T cells. This fetal cell microchimerism may have a direct impact on maternal health.

Is idiopathic chronic pancreatitis an autoimmune disease?

BACKGROUND & AIMS: The proportion of patients with idiopathic chronic pancreatitis (ICP) that have an autoimmune origin is unknown. Three forms of ICP have been described: pseudotumoral, duct-destructive, and usual chronic pancreatitis. The aim of this study was to identify autoimmune stigmata in the 3 forms. METHODS: All patients who underwent exploration for ICP were included. The following data were recorded: examination by an internal medicine specialist, autoantibodies and immunoglobulin screening, and pancreatic duct imaging. RESULTS: Sixty patients were included (pseudotumoral, n = 11; duct-destructive, n = 27; usual, n = 22). There were no significant differences among the 3 types with regard to sex ratio, age, frequency of acute pancreatitis, or obstructive jaundice. Pancreatic calcifications were seen only in the usual form (81%; P = .0001). Autoimmune disease was present in 10 patients: ulcerative colitis in 5 patients, primary sclerosing cholangitis in 2 patients, and Sjögren's syndrome, Hashimoto's thyroiditis, and Graves' disease in 1 patient each. Autoimmune diseases were not more frequent in patients with pseudotumoral (36%) or duct-destructive (19%) forms than in those with the usual form (5%, P = .06). Immunoglobulin G4 levels were increased in 2 of 6 in the pseudotumoral, 1 of 9 in the duct-destructive, and 0 of 12 patients in the usual group. Combining clinical and biochemical autoimmune parameters, 24 patients (40%) had at least 1 autoimmune marker or disease. CONCLUSIONS: Clinical or biochemical autoimmune stigmata are present in 40% of patients with ICP. Autoimmune mechanisms may be frequent in idiopathic pancreatitis.

Improvement of collagen-induced arthritis by active immunization against murine IL-1beta peptides designed by molecular modelling.

Interleukin-1beta (IL-1beta) is a crucial cytokine in inflammation processes and has been implicated in the pathogenesis of several chronic inflammatory diseases. Strategies designed to blocking IL-1beta by passive administration of inhibitors (mAbs, IL-1 receptor antagonist) have previously demonstrated efficacy in rheumatoid arthritis (RA). Using molecular modelling, we have defined three murine IL-1beta peptide regions characterized by their close proximity to the receptor. Synthetic peptides corresponding to these regions, in cyclic and linear form, were delivered as immunogens in Swiss mice, resulting in significant levels of autoantibodies directed against the native murine IL-1beta cytokine as determined by ELISA and by an assay for neutralization of IL-1beta biological activity. More importantly, one of the cyclic peptides showed a protective effect against inflammation and articular destruction in DBA/1 mouse collagen-induced arthritis, a model of RA. The high rate of success observed for active immunization against cytokine peptides in vivo suggests that the in silico approach to autoantigen design may be a promising avenue for the development of anti-cytokine immunotherapeutics.

Analysis of IGG and IGG4 in HIV-1 seropositive patients and correlation with biological and genetic markers.

We have compared the levels of immunoglobulins G (IgG) and G4 (IgG4) in extreme seropositive patients from the GRIV cohort consisting of 168 patients with slow progression (SP) and 60 with rapid progression (RP) as well as in 173 healthy controls. IgG levels were significantly higher in SP patients than in RP patients (P = 0.008), both higher than in seronegative individuals. IgG4 levels were significantly lower in SP patients than in RP patients (P = 0.001), both lower than in seronegative individuals. We tried to correlate these levels with biological parameters (CD4(+) and CD8(+) cells, total lymphocytes, white blood cell counts, percentage of CD4(+) cells, and viral load) as well as with genetic markers from Th1/Th2 cytokines (IL2, IL4, IL6, IL10, IL13, and IFNgamma). IgG levels were correlated with the percentage of CD4(+) cells in SP while IgG4 levels were correlated with CD8(+) cell count in SP and with percentage of CD4(+) cells in RP patients. Among the parameters measured in SP patients at the time of inclusion in the study, the best predictor of progression towards AIDS was the viral load, the best predictor for stability was CD4(+) cell count, but overall, the best predictor for SP evolution (stability vs. progression) appeared to be the percentage of CD4(+) cells. Interestingly, correlations between the levels of IgG or IgG4 and the cytokine gene polymorphisms were found, notably in the IL10 gene.

Free immunoglobulin light-chain serum levels in the follow-up of patients with monoclonal gammopathies: correlation with 24-hr urinary light-chain excretion.

In patients with light-chain myeloma or primary AL-amyloidosis, 24-hr light-chain excretion in the urine is considered an essential marker of the tumor mass. However, 24-hr urine collection and analysis may be cumbersome and prone to inaccuracy. Recently, a sensitive immunonephelometric assay for immunoglobulin free light chains (FLC) in the serum was developed. We sought to determine whether the serum level of monoclonal FLC could be used as an indicator of urinary excretion and disease evolution. Seven patients with light-chain myeloma and AL-amyloidosis were studied, all of which had a monoclonal FLC that could be detected in the urine using standard methods. In four of these patients, follow-up revealed a remarkable correlation between FLC serum levels and daily urinary excretions. The ratio of serum level to urinary light-chain excretion, although stable in a given patient, was extremely variable between patients. In the three remaining cases featuring hardly measurable amounts of light chain in the urine, the serum FLC assay proved sensitive enough for correlation with clinical events. Thus, immunonephelometric measurement of serum FLCs is a reliable method for the follow-up of patients with light-chain secreting monoclonal gammopathies.