Autoimmune hemolytic anemia (AIHA) is a disease process that involves the destruction of red blood cells mediated by the humoral immune system. It can be characterized as a cold agglutinin syndrome, paroxysmal cold hemoglobinuria, and warm, mixed type, and drug-induced AIHA. Although a well-established relationship exists between the presence of AIHA and lymphoproliferative malignancy, AIHA rarely presents in association with solid malignancies. An analysis of the limited number of published cases of AIHA in association with solid malignancies performed showed that AIHA may present before the diagnosis of a solid malignancy, concurrently with the presence of a solid malignancy, or even on resolution of a solid malignancy. Few cases of solid cancers associated with AIHA have been reported. AIHA rarely presents as a paraneoplastic syndrome indicating existence of a solid cancer. We report a case of inflammatory breast cancer with AIHA.

Discussion of the hematologic complications of vaccination for severe acute respiratory syndrome coronavirus-2 (COVID-19) has primarily focused on the development of vaccine-associated immune thrombosis with thrombocytopenia (VITT). Other hematologic complications are uncommon. We report the case of a patient who developed immunoglobulin G (IgG)-mediated autoimmune hemolytic anemia (AIHA) after the Moderna COVID-19 messenger ribonucleic acid (mRNA) vaccine.

In this study, we demonstrated that membrane immunofluorescence (MIF) with canine erythrocytes is a much more sensitive diagnostic technique compared with the Coombs test to detect auto-antibodies on RBC. We also demonstrate how the evaluation of the MIF test can be made more precisely which results in a more clear interpretation. Till nowadays the Evans syndrome (combined thrombocytopenia and anemia) is not very well diagnosed in dogs. Only a few studies with low animal numbers tested auto-antibodies on RBC and thrombocytes. Here we describe the frequency of Evans syndrome based on the evaluation of a large data set with 557 dogs. The novelty of the thesis also lies in making a research of the amount of CICs in sera of AIHA/AITP patients is described as well as the cytotoxic potential of patient’s sera for canine leucocytes. These new aspects of diagnosis (AIHA) and pathogenesis (AIHA/AITP) are not only relevant for dogs but also for humans and can be used for better differential diagnosis in medicine. The new findings with respect to circulating immune complexes and cytotoxicity are also offer new therapeutic concepts. Besides, the study has resulted in the characterization of monoclonal antibodies which allow for the detection of so far undetectable canine differentiation antigens (CD molecules) on canine erythrocytes (CD235) and thrombocytes (CD42a). The identified mAbs are useful in the identification of relevant target structures for autoantibodies on these cells.

Le syndrome d'Evans est défini par l'existence concomitante ou séquentielle de cytopénies auto-immunes, le plus souvent, anémie hémolytique et thrombopénie immunologique. Chez l'enfant, il peut être secondaire à une infection, une maladie auto-immune systémique ou un déficit immunitaire primitif. Alternativement, chez une grande partie des patients, l'étiologie n'est pas clairement identifiée. Les patients atteints de syndrome d'Evans présentent parfois d'autres atteintes, telles une auto-immunité d'organe, une lymphoprolifération bénigne ou un déficit immunitaire. L'objectif de ce travail était d'identifier des causes génétiques chez des enfants présentant un syndrome d'Evans sans étiologie sous-jacente identifiée. Nous avons centré notre étude sur des formes sévères à début pédiatrique en faisant l'hypothèse qu'une maladie monogénique serait plus fréquente dans ce groupe de patients. Nous avons mis à profit les technologies de séquençage haut débit « nouvelle génération » (NGS) pour réaliser et analyser le séquençage de l'exome de patients et de certains de leurs apparentés afin de mettre en évidence des gènes candidats potentiels. Ce travail a permis l'identification de 4 gènes candidats : LRBA, CTLA-4, STAT3 (mutations gain de fonction) et NFKBIA. L'implication des 3 premiers gènes dans de nouvelles maladies monogéniques où l'auto-immunité est au premier plan a été confirmée par d'autres équipes au cours de ce travail. Pour chacun de ces gènes, nous avons poursuivi 2 objectifs complémentaires : d'une part, tenter de valider l'implication des gènes identifiés dans la maladie des patients. Nous avons pour cela utilisé des approches et techniques variées : biochimie et protéomique afin d'identifier des partenaires protéiques, microscopie confocale pour localiser les protéines et leurs interactions, tests cellulaires in vitro pour mettre en évidence un défaut fonctionnel, marquages en cytométrie en flux pour identifier des modifications dans les sous-populations lymphocytaires. D'autre part, nous avons recherché d'autres mutations de ces gènes chez des patients de phénotype clinique similaire. Nous avons ainsi constitué et exploré 3 cohortes de patients présentant des mutations de LRBA, CTLA-4 ou STAT3. Nous avons rassemblé une cohorte de 18 patients porteurs d'une mutation de LRBA, répartis dans 11 familles. Cela nous a permis de préciser et d'étendre le spectre clinique de cette maladie de découverte récente, avec en particulier des atteintes articulaires sévères s'associant à un diabète précoce, ou des entéropathies. Nous avons identifié 15 nouvelles mutations de transmission autosomique récessive dans le gène LRBA, codant une protéine de fonction inconnue dont l'absence entraine une maladie principalement caractérisée par une poly-auto-immunité. Nous avons identifié 29 partenaires protéiques potentiels de LRBA et précisé la localisation de LRBA dans les différents compartiments cellulaires. Nous avons également établi une cohorte de 12 patients dans 10 familles présentant un déficit en CTLA-4 par haplo-insuffisance. Au delà de la mise en évidence de 9 nouvelles mutations, nous avons décrit une famille où la variation est transmise de façon autosomique récessive. Dans les déficits en LRBA et CTLA-4, nous avons mis en évidence une diminution du pourcentage de lymphocytes T régulateurs parmi les PBMC et une diminution de l'expression de CTLA-4 dans les lymphocytes T activés. Ceci corrobore l'interaction entre ces 2 protéines décrite en parallèle par une autre équipe. Nous avons montré que les spectres cliniques des déficits en LRBA et CTLA-4, fortement chevauchant dans les premières descriptions publiées, pourraient se différencier, malgré l'implication des lymphocytes T régulateurs dans ces 2 maladies. (...) / Evans syndrome is defined by the occurence of autoimmune cytopenias, either at the same time or sequential, mainly autoimmune hemolytic anemia and immune thrombocytopenia. In children, it may be secondary to infections, systemic autoimmune disease, or primary immune deficiency, though in most patients, its etiology isn't obvious. Patients affected with Evans syndrome can also present other features, such as autoimmunity toward a particular organ, benign lymphoproliferation or immunodeficiency. The main goal of this work was to identify genetic causes in children presenting an Evans syndrome without a known underlying etiology. We focused our study on severe, early onset forms of the disease, with the hypothesis that a monogenic disease would be more frequent in this group of patients. Taking advantage of high throughput "Next Generation" sequencing (NGS) techniques, we sequenced and analyzed exome from patients and their relatives in search for adequate candidate genes. We identified 4 candidate genes: LRBA, CTLA-4, STAT3 (gain-of-function mutations), and NFKBA. Implication of the first 3 genes in new monogenic diseases with autoimmunity as a key feature was also confirmed by others during the course of this work. For each gene, we pursued 2 complementary goals: First, we sought to validate the implication of the gene in the patients' disease. To do so, we used various techniques and approaches: biochemistry and proteomics to identify protein partners, confocal microscopy to localize proteins and interactions, in vitro cellular assays to bring to light functional defect, flow cytometry to identify changes in lymphocytes subpopulations. We also looked for other mutations of each gene in patients with a similar clinical presentation. Hence we created and explored 3 cohorts of patients presenting with mutations of LRBA, CTLA-4 or STAT3. We constituted a cohort of 18 patients with LRBA mutations within 11 families. We then were able to precise and extend the clinical spectrum of this recently described disease. In particular, we observed patients with severe chronic arthritis associated with diabetes mellitus or enteropathies. We identified 15 new mutations of autosomal recessive transmission in the LRBA gene, coding a protein of unknown function, which absence is responsible for a disease mainly characterized by autoimmune features. We identified 29 candidate protein partners of LRBA and precized LRBA localisation in cell compartiments. We also established a cohort of 12 patients within 10 families presenting CTLA-4 haploinsufficiency. Beyond describing 9 new mutations, we report a family with autosomal recessive transmission.In LRBA and CTLA-4 deficiencies, we showed a decrease of regulatory T lymphocyte subset proportion among PBMC and a decrease of CTLA-4 expression in activated T cells. These results support the interaction between these 2 proteins, described concurrently by another team. We showed that the clinical spectra of these 2 diseases, although widely overlapping in first published reports, could be different despite a role of regulatory T cells in both. Hence, organ-specific autoimmunity and lymphoproliferation are more frequent in LRBA deficiency whereas granuloma and hypogammaglobulinemia are more present in CTLA-4 deficiency. Theses results suggests a role of genetic modifyers, which remain to identify. Among our cohort of patients with Evans syndrome, we also identified 5 patients within 5 families presenting gain-of-function mutations of STAT3. 3 of those mutations were reported by others during our work and appeared de novo in our patients. Functional validation of the 4th one is in progress. The last mutation follows a recessive transmission and could exemplify a new transmission modality of this disease. (...)