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International audience; Monoclonal gammopathies of renal significance (MGRS) encompass a remarkable variety of kidney diseases that result from intrinsic nephrotoxic properties of certain monoclonal Igs or their subunits. Effective disease-modifying treatments rely on the targeting of a malignant B-cell clone that may be demonstrable but often is quite hypothetical. Hence, convincing arguments for the genuine monoclonal character of the causative mono-isotypic Ig tissue deposits is needed for design of appropriate treatment strategies. The purpose of this article was to critically analyze distinct situations of suspected MGRS that occur in the practice of pathologists, nephrologists, hematologists, and immunologists. A particular focus of interest is the group of conditions known as proliferative glomerulonephritis with mono-isotypic immunoglobulin deposits (PGNMIDs), which illustrates the difficulties and ambiguities surrounding a definitive assignment of MGRS status.

Introduction Les patients atteints de lupus systemique sont a haut risque d’infection invasive a pneumocoque. La vaccination anti-pneumococcique sequentiel (i.e. vaccin conjugue 13-valents (VPC13) puis vaccin polysaccharidique 23-valents (VPP23)) est recommandee chez ces patients. L’objectif de ce travail etait d’analyser le taux de protection anti-pneumococcique induite a long terme par cette strategie vaccinale et d’identifier les facteurs associes a la protection. Patients et methodes Conformement aux recommandations la vaccination anti-pneumococcique etait proposee a tous les patients suivis pour un lupus systemique admis de facon consecutive dans notre unite d’hospitalisation de jour (HDJ) entre avril et decembre 2015. Les patients recevaient le vaccin VPC13 puis le vaccin VPP23 8 semaines apres. La protection immune anti-pneumocoque, definie par un titre d’IgG specifique ≥ 1.3 μg/ml pour au moins 70 % des 7 serotypes pneumococciques (4, 6B, 9 V, 14, 18 C, 19F, 23F), etait evaluee avant la premiere injection vaccinale puis a 2 mois, 6 mois, 12 mois, et 36 mois, definissant la protection a long terme. Resultats La vaccination anti-pneumococcique etait proposee a 37 patients suivis pour un lupus. Parmi ceux-ci, 8 ont refuse la vaccination, 7 ont accepte la vaccination mais ont refuse le monitoring de la reponse immune et 1 etait deja vaccine. Vingt et-un patients lupiques (40 [25–75] ans ; 85,7 % femmes) ont finalement recu les vaccins VPC13/VPP23 dans le cadre de cette etude. Seulement 10 (47,6 %) patients avaient une protection immune anti-pneumococcique persistante 36 mois apres la vaccination (protection a long terme, LTP). Onze patients n’avaient pas de protection a long terme (NLTP), avec une seroconversion qui n’apparaissait jamais (n = 6) ou transitoirement (n = 5). Les caracteristiques cliniques et immunologiques ainsi que les traitements recus n’etaient pas differents entre les patients proteges et non proteges a la seule exception des taux d’IgG2 seriques avant la premiere injection vaccinale qui etaient significativement plus bas dans le groupe NLTP (1,45 [1,30–1,82] vs 3,30 [2,92–4,44] g/L, p Conclusion Le benefice de la vaccination anti-pneumococcique sequentielle VPC13/VPP23 dans le lupus systemique est limite. Les taux seriques d’IgG2 avant la vaccination identifient les patients beneficiant ou non d’une protection post vaccinale a long terme.

Introduction Depuis 2013, le Haut Conseil de la Sante publique recommande que les patients traites par immunosuppresseur, biotherapie et/ou corticotherapie pour un lupus systemique (LS) soient systematiquement vaccines contre le pneumocoque. Le schema vaccinal propose est une dose de vaccin conjugue 13-valent (PCV13-PREVENAR) suivie, deux mois plus tard, d’une dose de vaccin non conjugue polysaccharidique 23-valent (PPV23-PNEUMO 23). Il n’y a toutefois aucune donnee publiee sur l’immunogenicite de ce schema dans cette population. L’objectif de cette etude est de mesurer la reponse vaccinale 2 et 12 mois apres une vaccination sequentielle par PCV13/PPV23 et analyser les determinants cliniques et immunologiques associes a la protection vaccinale anti-pneumococcique chez les sujets lupiques. Patients et methodes Cette etude monocentrique observationnelle non controlee a ete realisee d’avril a decembre 2015 dans 1 service de medecine interne (Paris). La vaccination anti-pneumococcique et le suivi de la reponse immune sur 12 mois ont ete proposes a tous les patients lupiques admis en hopital de jour (HDJ) pour le suivi de leur maladie et candidats a la vaccination. Les donnees cliniques et biologiques etaient collectees et le taux d’anticorps anti-pneumococcique (Elisa) etait mesure a m0, m2 et m12. Etait exclu tout patient en poussee de LS, ayant recu une injection de rituximab durant l’annee precedente ou ayant ete deja vaccine contre le pneumocoque. La protection vaccinale etait definie par une concentration d’IgG ≥ 1,3 μg/mL pour au moins 70 % des 7 serotypes pneumococciques (4, 6B, 9V, 14, 18C, 19F, 23F) testes. Les patients etaient dit « proteges a long terme » (PLT) si la protection vaccinale etait observee a m2 et m12, « proteges a court terme » (PCT) si la protection etait observee a m2 mais perdue a m12, et « non proteges » (NP) si aucune protection vaccinale n’etait observee a m2 et m12. Resultats Au total, 37 patients lupiques candidats a la vaccination anti-pneumococcique conformement aux recommandations ont ete admis en HDJ pour le suivi habituel de leur maladie sur la periode consideree. Parmi eux, 8 patients ont refuse la vaccination, 7 ont accepte la vaccination mais, ont refuse le suivi immunologique et 1 etait deja vaccine contre le pneumocoque. Vingt et un patients (40 [25–75] ans ; 85,7 % femme ; SELENA-SLEDAI score a 1 [0–4]) ont ete inclus. La duree mediane du LS etait de 11 [1–32] ans. Tous les patients avaient recu une corticotherapie pendant une duree mediane de 2 ans [0,5–13] et 12 (57,1 %) etaient toujours sous corticoides a la dose quotidienne de 10 mg [7–15] a l’inclusion. Quinze patients (71,4 %) avaient recu un immunosuppresseur pendant 3 ans [1–14] et 9 (42,9 %) etaient toujours traites. Trois (14,3 %) patients avaient presente une infection a pneumocoque documentee. A m0, aucun patient n’etait protege contre le pneumocoque. La protection etait retrouvee chez 17 (81 %) patients deux mois apres l’injection de PCV13 (M2), mais n’etait plus presente que chez 12 (57,1 %) patients a m12 (PLT, n = 12 et PCT, n = 5). Chez 4 patients, aucune protection n’etait observee a m2 et m12 (NP, n = 4). Les criteres cliniques consideres (âge, duree de la maladie, traitement, duree cumulee des traitements, SLENA-SLEDAI) ne permettaient pas de differencier les patients PLT, PCT et NP. Un taux faible de lymphocytes B naifs, memoires et memoires switches, un taux faible de lymphocytes T CD4+ et une hypogammaglobulinemie Conclusion Pres de la moitie des patients lupiques vaccines contre le pneumocoque conformement aux recommandations (PCV13/PPV23) n’ont pas de reponse protectrice a m12. Un taux faible de lymphocytes B et T CD4+, une hypogammaglobulinemie profonde et un faible titre d’IgG dirigee contre le serotype 19F a m2 de la 1re injection vaccinale (PCV13) sont associes a l’absence de protection.

International audience; Results of Phase III studies involving a large number of Alzheimer's disease (AD) patients treated by passive immunotherapy with humanized anti-amyloid β monoclonal antibodies have recently been released. These approaches failed to show a significant clinical benefit in patients with mild to moderate AD. The most considered explanation is that the patients have been treated too late. Whereas targeting patients at asymptomatic stages of the disease is a critical step in the goal of improving the efficacy of such antibody-based strategies, several other important factors should be considered in the development and clinical evaluation of anti-amyloid β immunotherapies, including the as yet poorly understood relationship of AD with the immune system and the importance of cerebral amyloid angiopathy. Better understanding the role of immune responses in AD and their impact on immunotherapy appears essential in the design of alternative or combinatorial immunotherapy approaches in AD, which may imply effectors other than antibodies and even additional antigenic targets.

Ig-related renal diseases occurring in lymphoplasmacytic disorders (LPD) cover a wide spectrum of renal lesions. Except for cast nephropathy, which is almost specific for multiple myeloma, similar renal lesions caused by deposition or precipitation of monoclonal Ig-related material may occur in the various types of LPD. Because the secreted Ig provides the link between the LPD and the kidney disease, the renal outcome is linked to efficacy of chemotherapy. In the past 10 years, considerable advances have occurred in chemotherapy regimens with the advent of new classes of drugs, which already result in markedly improved renal and vital survival.

Light chain deposition disease (LCDD) and light chain amyloidosis (AL) are disorders of monoclonal immunoglobulin deposition in which normally soluble serum precursors form insoluble deposits in tissues. A common feature in both is the clonal proliferation of B-cells that produce pathogenic light chains. However, the deposits in LCDD differ from those in AL in that they are ultrastructurally granular rather than fibrillar and do not bind Congo red or colocalize with amyloid P component or apolipoprotein E. The reason(s) for their differences are unknown but are likely multifactorial and related to their protein conformation and their interaction with other molecules and tissue factors in the microenvironment. Knowledge of the primary structure of the light chains in LCDD is very limited. In the present study two new κ 1 light chains from patients with LCDD are described and compared to seven other reported κ-LCDD proteins. The N-terminal amino acid sequences of light chain GLA extracted from the renal biopsy and light chain CHO from myocardial tissue were each identical to the respective light chains isolated from the urines and to the V-region amino acid sequences translated from the cloned cDNAs obtained from bone marrow cells. The germline V-region sequences, determined from the genomic DNA in both and in MCM, a previously reported κ 1 LCDD light chain, were identical and related to the L12a germline gene. The expressed light chains in all three exhibit amino acid substitutions that arise from somatic mutation and result in increased hydrophobicity with the potential for protein destabilization and disordered conformation.

A 45-year-old white woman was found to have microscopic hematuria during her annual physical examination. After a negative urologic workup, she returned 5 months later with nephrotic syndrome, renal insufficiency, and hypocomplementemia. Renal biopsy showed a nodular sclerosing glomerulopathy that could not be further characterized because of inadequate tissue for immunofluorescence. The patient returned 8 months later with chronic renal failure. A repeat renal biopsy showed deposits composed of immunoglobulin G (IgG) heavy chain and complement components C3 and C1 along glomerular, tubular, and vascular basement membranes, with negativity for kappa and lambda light chains, findings consistent with heavy chain deposition disease (HCDD). The heavy chain subclass was exclusively IgG3. Staining with monoclonal antibodies to epitopes of the constant domains of IgG heavy chain showed a CH1 deletion, indicating a truncated heavy chain. On review of the previously reported cases of HCDD, common clinical presentations include nephrotic syndrome, renal insufficiency, hematuria, and, in some cases, hypocomplementemia. In most patients, the hematologic disorder is mild, without overt myeloma. Light microscopy shows a nodular sclerosing glomerulopathy, and heavy chain deposits are detectable within basement membranes throughout the kidney by immunofluorescence and electron microscopy. There is no effective treatment for this condition, and virtually all patients progress to chronic renal failure.

Sera from 20 patients with bullous pemphigoid (BP) were analyzed for the subclass distribution of IgG autoantibodies by Western immunoblotting of normal human heat-separated epidermal extracts. Strips were sequentially probed with patient sera, monoclonal antibodies (Mab) anti-human IgG 1–4 , and a labeled anti-mouse Ig. The relative dilutions of each subclass-specific Mab were determined in dot immunobinding experiments in order to give uniform reactivity to the corresponding human IgG subclass. Circulating BP autoantibodies reacting with the major BP antigen of 220 kDa and/or a 165-kDa band showed a stricking predominance of IgG 4 . Overall, IgG 4 was the major subclass reactive with the 220-kDa band, whereas, in addition to IgG 4 , IgG 1 and IgG 2 were frequently represented in the response to the 165-kDa band. Complement fixation of circulating BP antibodies was studied by complement indirect immunofluorescence using human serum as source of complement and FITC goat anti-human C3, C1q, and C4, on normal human skin substrate. When circulating BP antibodies contained IgG 1 or IgG 2 in addition to IgG 4 , they fixed C3 and, in some cases, C1q and C4, suggesting complement activation by either the classical or the alternate pathway.

Introduction Alors que le systeme immunitaire adaptatif tolere naturellement les antigenes du soi, plusieurs etudes recentes suggerent qu’il est capable de reagir au peptide amyloide Aβ, aussi bien dans des modeles animaux transgeniques qu’au cours de la maladie d’Alzheimer humaine. Ainsi, des methodes d’immunisation classiques induisent des reponses ayant un effet sur le plan pathologique et eventuellement clinique. La mise au point de vaccins therapeutiques s’avere cependant difficile car les reponses cellulaires T peuvent se compliquer de meningoencephalites graves. Par ailleurs, si les anticorps anti-Aβ seuls semblent efficaces contre l’accumulation des plaques seniles, leur effet therapeutique clinique est moins certain. Dans l’ensemble, il apparait indispensable de mieux connaitre les relations entre le systeme immunitaire et le peptide Aβ pour concevoir des approches immunotherapeutiques efficaces et sures. Un interet particulier a ete porte aux cellules T regulatrices (Treg), responsables des principaux mecanismes de la tolerance immunitaire peripherique. Materiel & methodes Des souris C57BL/6 sauvages ou doubles transgeniques APPPS1 (APP K670N/M671L et PS-1 L166P) ont ete traitees ou non a l’âge de 8 ou 16 semaines par un anticorps anti-CD25 (PC61) pour depleter de facon transitoire les Treg. L’effet de cette depletion sur l’activation des reponses T CD4+ anti-Aβ a ete analyse apres vaccination par Aβ42 en presence d’adjuvant complet de Freund. En parallele, l’impact de la depletion des Treg sur l’evolution naturelle de la maladie a ete etudie par analyses histologiques et comportementales sur un groupe de souris APPPS1 traitees ou non par PC61 mais non-vaccinees. Resultats Apres suppression des Treg les reponses proliferatives T CD4+ anti-Aβ post-vaccinales sont plus augmentees chez les souris transgeniques APPPS1 que chez les souris sauvages. D’autre part, nos resultats preliminaires suggerent que la tolerance due aux cellules Treg peut favoriser la progression des signes pathologiques. Discussion Les cellules Treg inhibent les reponses T CD4+ anti-Aβ se developpant spontanement au cours de la maladie, et pourraient ainsi contribuer a la physiopathologie de la maladie d’Alzheimer. La depletion des cellules T regulatrices represente donc un outil therapeutique potentiel, sous reserve que les reponses immunitaires chez l’homme soient semblables a celles du modele murin APPPS1. Des travaux recents vont dans ce sens, montrant que les reponses immunitaires adaptatives contribueraient au controle des depots amyloides.

The authors describe a 54-year-old woman presenting with proteinuria, hematuria, and hypocomplementemia whose renal biopsy results showed diffuse increase in mesangial matrix and nodular formations in several glomeruli with the deposition of immunoglobulin gamma3-heavy-chain and complement components C1q and C3 in the glomeruli and on the tubular basement membranes, without associated light-chain deposits. Staining for the constant domains of gamma-heavy-chain showed a deletion of the first constant domain (CH1). These findings were consistent with those of gamma-heavy-chain deposition disease (gamma-HCDD). The patient was treated monthly with melphalan and prednisolone although a bone marrow aspirate did not show findings suggestive of plasmacytoma. Six courses of melphalan and prednisolone therapy resulted in a marked reduction of urinary protein excretion and marked rise of complement levels. The current case is the fourth HCDD patient reported featuring gamma3-heavy-chain deposition who showed severe hypocomplementemia and responded to chemotherapy with improved renal parameters and complement levels. A review of previously reported cases of HCDD showed that some but not all HCDD cases were associated with hypocomplementemia. The authors also discuss here the relationship of HCDD to hypocomplementemia.

Measurement of antibodies to the capsular polysaccharide polyribosylribitolphosphate (PRP) of Haemophilus influenzae type b by ELISA is made difficult by the poor binding of this antigen to the solid phase. Six coating conditions were compared using immune and non-immune human sera. Direct coating with PRP was inefficient. Precoating with protamine or poly-L-lysine (PLL) yielded irreproducible results and high background levels. Assays with PRP conjugated with PLL as coat were not sensitive enough. In addition, anti-PRP antibodies, especially those belonging to the IgM class, crossreacted with PLL. Coating with avidin or streptavidin followed by incubation with biotin-coupled PRP was not satisfactory either, due to binding of certain sera in the absence of PRP. Coating with PRP coupled to tyramine resulted in low backgrounds and acceptable specific binding levels. However, the finding that the binding of a few sera was only partially inhibited by soluble PRP led us to include an inhibition step in every experiment. Only optical densities inhibited by the antigen were taken into account. In view of the lack of parallelism of dilution curves from different sera, no attempt was made to express the results in weight units. They were expressed in arbitrary units calculated by comparison with internal standards. Under such conditions, the assay permitted a reproducible (interassay coefficients of variation around 10%) determination of PRP-Ab belonging to the various immunoglobulin classes and IgG subclasses and showed a good correlation with results obtained using the Farr assay.

International audience; A competitive indirect ELISA is described for the measurement of IgG4 levels. It uses a monoclonal anti-subclass and antibody and purified monoclonal IgG4 as standards. This method is sensitive and reproducible and more accurate than hemagglutination inhibition and radial immunodiffusion. Serum IgG4 levels in 173 normal adults were less than 0.01-2.1 mg/ml (mean 0.30 mg/ml) in women and less than 0.01-1.87 mg/ml (mean 0.465 mg/ml) in men.

International audience; Serum IgG subclass levels were measured using an indirect competitive immunoenzymatic assay with monoclonal antibodies in 221 patients affected with definite immunodeficiency (ID) syndromes and 229 patients presenting with infection patterns suggestive of ID, but with normal immunoglobulin class levels and no clear evidence of ID. In common variable ID and IgG-IgA deficiency with normal or high IgM, subclass imbalance (mostly IgG1-IgG3 or IgG2-IgG4 deficiency) was the rule, with a higher incidence of severe infections in IgG2-IgG4 defects. One-fifth of patients with IgA deficiency, especially those with autoimmune cytopenia, had subclass deficiencies with no significant correlation with the occurrence of infections. Subclass (mostly IgG2-IgG4) deficiencies were also observed in severe combined ID, defective expression of HLA class II antigens, chronic mucocutaneous candidiasis, and IgM deficiency. Subclass levels were normal in all but one (who was IgG3 deficient) patient with the Wiskott-Aldrich syndrome and in the Buckley's syndrome, except for an unusual patient who presented with low IgG and IgA levels. Subclass (mainly IgG2) deficiency occurred in 24% of infected patients without known ID.

The distribution of human IgG subclasses among the glomerular deposits of 53 patients with glomerulonephritis was examined by immunofluorescence (IF) with subclass-specific monoclonal antibodies (Mab). A subclass restriction was observed in idiopathic membranous nephropathy (MN) with glomerular deposits predominantly containing IgG4 (81% of the studied biopsies) and IgG1 (75%). In de novo MN, occurring after transplantation, the restriction was markedly different, with a predominance of IgG1 (100%) and IgG2 (69%). In anti-glomerular basement membrane (a-GBM) nephritis the restriction was considerable with deposits containing almost exclusively IgG1 (91%) and IgG4 (73%). The same restriction was observed for circulating anti-GBM antibodies detected by indirect IF assay. By contrast IgG1, IgG2, and IgG3 deposits were identified in lupus proliferative glomerulonephritis. Serum IgG subclass levels were measured in 29 patients with idiopathic MN and a-GBM nephritis by an indirect competitive immunoenzymatic assay using Mab. Mean percentage of IgG2 serum level was significantly lower in patients. In spite of high variations from patient to patient, a serum IgG subclass imbalance was clearly present in 10 cases with low IgG2 and high IgG1 and IgG3 levels. The imbalance in these patients was not due to urinary loss since it was observed with a similar frequency in hypo- and normoimmunoglobulinemic patients. In 5 out of these 10 patients IgG2 levels were very low, analogous to those observed in selective IgG2 deficiency. Whether the important subclass restriction of glomerular IgG (in which patterns differed according to the type of glomerulonephritis) and the serum subclass imbalances were due to a clonally restricted antibody response to a particular antigen or to a host immune response defect, or both, remains to be elucidated.