Alain Chevailler

Endogenous PTX3 translocates at the membrane of late apoptotic human neutrophils and is involved in their engulfment by macrophages.

Neutrophils are short-lived innate immune cells that rapidly die by apoptosis. A rapid and efficient clearance of apoptotic cells is crucial to avoid autoimmunity. This process involves cell alterations, endocytic receptors expressed by phagocytic cells and soluble bridging molecules (opsonins) that facilitate internalization of apoptotic cells by phagocytes. Neutrophils constitutively express the prototypic long pentraxin PTX3 that binds to apoptotic cells and modulates their clearance. We thus evaluated whether endogenous PTX3 may interfere with the capture of apoptotic neutrophils. We observed that PTX3 accumulates in blebs at the surface of late apoptotic neutrophils, resulting from its active translocation from granules to the membrane. A neutralizing anti-PTX3 monoclonal Ab (mAb) inhibits the capture of late apoptotic neutrophils by macrophages. This study shows that intracellular PTX3 translocates at the surface of late apoptotic neutrophils and acts as an ‘eat-me’ molecule for their recognition and capture by macrophages.

Antineutrophil Cytoplasmic Autoantibodies: How Should the Biologist Manage Them?

Antineutrophil cytoplasmic antibodies (ANCA) are directed against enzymes found in the granules of the polymorphonuclear (PMN) leukocytes. They are detected by indirect immunofluorescence microscopy assays on human ethanol fixed neutrophils. Three different fluorescence patterns can be distinguished: a cytoplasmic pattern (cANCA), a perinuclear pattern (pANCA), and an atypical pattern (aANCA). The use of other fixatives, e.g., formalin and methanol, allows differentiation between the pANCA and the antinuclear antibodies. ANCA specificity is determined by solid phase assays (ELISA, immunodot, and multiplex assay). ANCA with high titres and defined specificities (antiproteinase 3 [PR 3] or antimyeloperoxidase [MPO]) are proven to be good serological markers of active primary systemic vasculitis: c/PR 3-ANCA for Wegener’s granulomatosis and p/MPO-ANCA for microscopic polyangiitis. The former have higher sensitivity and specificity for Wegener’s granulomatosis than the latter for microscopic polyangiitis. ANCA with low titres and unknown specificity have been detected in a wide range of inflammatory and infectious diseases leading to a critical reappraisal of the diagnostic significance of ANCA testing. Physicians must keep in mind the possible occurrence of infectious diseases like subacute endocarditis that could be dramatically worsened by irrelevant immunosuppressive therapy. ANCA findings in certain manifestations, such as the pulmonary-renal syndrome in which massive pulmonary hemorrhage can quickly be life-threatening, warrant ANCA testing as an emergency test for patient care.

Prevalence of Autoantibodies to Cyclic Citrullinated Peptide in Patients with Rheumatic Diseases other than Rheumatoid Arthritis: A French Multicenter Study

Our objective was to evaluate the prevalence of autoantibodies to cyclic citrullinated peptides (anti-CCP aAbs) in a cohort of patients with a variety of inflammatory or non-inflammatory rheumatic diseases other than rheumatoid arthritis (RA). Six hundred and nine serum samples were tested for anti-CCP aAbs and for rheumatoid factor (RF) using enzyme-linked immunosorbent assays and immunonephelometry. The prevalence of anti-CCP aAbs and RF reached 10% and 25%, respectively, using the positive cutoff value suggested by the manufacturers. Using a higher cutoff value (50xa0U/ml) for both aAbs, the prevalence was lower with 6% and 16%, respectively. The specificity of both markers for RA thus reached 94% and 84%, respectively. Anti-CCP aAbs were found to be elevated in inflammatory and also in non-inflammatory rheumatic diseases in the same proportion. Clinical data obtained for 36 positive patients showed that 17% developed RA within 5xa0years. In conclusion, anti-CCP aAbs are clearly more specific than RF for RA. Follow-up of anti-CCP aAbs-positive patients with inflammatory or non-inflammatory rheumatic diseases other than RA could be important considering the predictive value of these aAbs for the development of RA.

Gelatinous Transformation of the Bone Marrow: Manifestation of an Acute Leukemia?

Gelatinous transformation of the bone marrow in a 79-year-old patient was observed. It was associated with acute leukemia diagnosed on the biopsy of a vertebral body, indicated by previous Indium-transferrin scintigraphy. Though the lesion is usually associated with severe weight loss and cachexia, the rare cases of gelatinous transformation reported among patients with malignant disease are summarized. It is suggested that metastatic changes by blast cells in acute leukemia may lead to gelatinous transformation of bone marrow but this remains to be investigated.

Detection of Anti-Pentraxin-3 Autoantibodies in ANCA-Associated Vasculitis.

Objectives Pentraxin 3 (PTX3), in common with myeloperoxidase and proteinase 3, is stored in human neutrophil granules and is expressed on apoptotic neutrophil surface. We therefore investigated the presence of anti-PTX3 autoantibodies (aAbs) in the sera of antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients. Methods Presence of anti-PTX3 autoantibodies was analysed by a specific enzyme-linked immunosorbent assay in sera from 150 patients with microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA), and in sera of 227 healthy subjects (HS), 40 systemic sclerosis (SSc) patients, and 25 giant cell arteritis patients (GCA). Using indirect immunofluorescence on fixed human neutrophils, we also analyzed the staining pattern associated with the presence of anti-PTX3 aAbs. Results Anti-PTX3 aAbs were detected in 56 of 150 (37.3%) of the AAV patients (versus 12 of 227 (5.3%) of HS, p<0.001) and, interestingly, in 7 of 14 MPO and PR3 ANCA negative AAV patients. Moreover, by indirect immunofluorescence on fixed neutrophils, anti-PTX3 aAbs gave rise to a specific cytoplasmic fluorescence pattern distinct from the classical cytoplasmic (c-ANCA), perinuclear (p-ANCA), and atypical (a-ANCA) pattern. Anti-PTX3 aAbs levels were higher in patients with active AAV as compared to patients with inactive disease. Conclusion Our work suggests that PTX3 is as a novel ANCA antigen. Anti-PTX3 aAbs appear thus as a promising novel biomarker in the diagnosis of AAV, including in patients without detectable MPO and PR3 ANCA.

Heterogeneous clinical spectrum of anti-SRP myositis and importance of the methods of detection of anti-SRP autoantibodies: a multicentric study.

Anti-signal recognition particle (SRP) antibodies are important serological markers for the diagnosis and the prognosis of idiopathic inflammatory myopathy (IIM), especially to distinguish immune-mediated necrotizing myopathy (IMNM). This study was set up to investigate the phenotype associated with anti-SRP antibodies and to evaluate the methods for detecting these antibodies. Clinical and biological data were retrospectively obtained from 60 adult patients with anti-SRP antibodies detected by a dot immunoassay from 12 centers. Thirty-six (60xa0%) out of these 60 patients suffered from an IIM, and among them, 21 patients were diagnosed as IMNM. Among patients with a definite IIM, proximal weakness and myalgia were prominent symptoms at the time of diagnosis. Only few patients displayed severe extra-muscular symptoms such as cardiac involvement or severe myositis. Mean creatine kinase levels were high for all patients except for two of them. When testing by indirect immunofluorescence (IIF) on HEp2 cells, the fraction of patients displaying the typical anti-SRP fine speckled staining of the cytoplasm was higher in patients with IIM (30/36) (83xa0%) than in patients with non-IIM (3/24) (12.5xa0%) (pxa0<xa00.0001). Thirty (91xa0%) out of 33 patients with a positive immunodot and a characteristic IIF cytoplasmic staining suffered from a clinical definite myositis, whereas only 6 (22xa0%) out of 27 patients with a positive immunodot but a negative cytoplasmic pattern suffered from a myositis (pxa0<xa00.00001). This series highlights the strong heterogeneity of anti-SRP positivity that encompassed IMNM and non-IMNM and supports the necessity of considering both IIF and dot immunoassay to confirm the diagnosis of anti-SRP-associated myositis.

Are immunoglobulin A anti-gliadin antibodies helpful in diagnosing coeliac disease in children younger than 2 years?

ABSTRACT The usefulness of immumoglobulin (Ig) A antibodies to gliadin (AGA-IgA) in addition to IgA anti-endomysium and tissue transglutaminase antibodies was evaluated in 4122 children younger than 2 years with a suspicion of coeliac disease (CD). Eight percent (312/4122) displayed IgA anti-endomysium and/or IgA anti-tissue transglutaminase, whereas 2.1% (85/4122) displayed only AGA-IgA. Clinical data were obtained for 62 of 85 children with isolated AGA-IgA, and 33 children underwent a duodenal biopsy. Histologically proven CD was established for 5 patients, whereas 57 children were diagnosed to experience other diseases. The systematic detection of AGA-IgA using native gliadin conferred no additional diagnostic benefit for the diagnosis of CD in children younger than 2 years of age, except for rare cases.

Apport des tests de quantification de la libération d’interféron gamma par les lymphocytes T sensibilisés pour le diagnostic des infections tuberculeuses

Resume L’intradermoreaction cutanee a la tuberculine, couramment utilisee depuis un siecle pour le diagnostic d’infection tuberculeuse, presente de nombreux inconvenients. De nouveaux tests diagnostiques ont ete recemment introduits. Ils mesurent soit la production d’interferon-γ dans le sang total, soit le nombre de lymphocytes T producteurs d’interferon-γ apres stimulation in vitro par des proteines specifiques de M. tuberculosis, absentes du BCG et de la plupart des mycobacteries atypiques. Le gain en specificite permet de reduire les resultats faux positifs chez les sujets vaccines, evitant ainsi le cout de chimioprophylaxies inutiles et potentiellement toxiques. Le gain en sensibilite, identifiant les infections tuberculeuses latentes parmi les sujets ayant une IDR faussement negative, permet d’accroitre les performances diagnostiques dans les populations les plus a risques de progresser vers la tuberculose maladie, a savoir les patients immunodeprimes. L’evaluation de ces tests doit desormais se focaliser sur certains points qui restent a preciser : leur sensibilite chez l’enfant et le sujet immunodeprime, leurs valeurs predictives positive et negative et l’interpretation de leur variation eventuelle au cours du temps, que les patients soient traites ou non.

Microbiotes, poumon et aménagement des interfaces. Nouveaux regards sur l’immunologie, et peut-être sur l’homme ?

Resume S’interesser au monde des microbiotes suppose d’abord d’essayer de discerner les limites et difficultes des methodes en permettant l’etude. Au niveau pulmonaire, le microbiote semble etre chez le sujet sain une expansion essentiellement bronchique de celui de l’oropharynx, cantonnee par l’epuration muco-ciliaire et la pauvrete des ressources disponibles localement. Les circonstances pathologiques agiront en favorisant une expansion plus ou moins globale et/ou une modification de sa repartition pouvant aller jusqu’a une perte de sa diversite. La pauvrete naturelle de ce microbiote nous incite, d’une part, a reconsiderer l’organisation de nos societes, inadaptee par sa concentration des individus ; et d’autre part, pour l’immunologiste, l’incite a reconsiderer l’amenagement des interfaces de notre organisme avec son environnement et a repenser le systeme immunitaire, et l’enseignement de la discipline, en ouvrant peut-etre ainsi une nouvelle periode dans l’histoire de la discipline.

Immunosénescence : vieillissement « et » ou « du » système immunitaire

Resume La plus grande sensibilite aux infections, aux tumeurs, aux maladies auto-immunes et la moins bonne reponse vaccinale sont les caracteristiques de la reponse immunitaire du sujet âge. Cette tranche de population en pleine expansion jusqu’en 2014 dans les societes industrielles, presente une plus grande frequence de comorbidites, qui sont autant de facteurs aggravants de la deficience de la reponse immunitaire identifiee sous le vocable d’immunosenescence. Pour en rendre compte, il faut envisager la dialectique de la participation du systeme immunitaire au processus de vieillissement physiologique et les consequences de ce dernier sur la reponse immunitaire dans ses branches innee et adaptative, avec des facteurs genetiques, epigenetiques et environnementaux intriques. L’etude de nombreux parametres immunitaires a permis d’identifier comme facteurs predictifs de vieillissement du systeme immunitaire une plus grande frequence de lymphocytes T CD8+CD28-, une faible reponse proliferative, un rapport CD4/CD8 bas (