autoimmune hemolytic anemia

Background: Like other viruses, the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) appears to be responsible for several autoimmune complications. The occurrence of autoimmune hemolytic anemia has been described in several case reports. This AIHA was also noticeable by the important number of blood transfusions required for COVID-19 (coronavirus disease 2019) patients. By investigating RBC coating autoantibodies, this article attempts to clarify the autoimmune aspect of the anemia in the context of SARS-CoV-2 infection. Results: A large population of COVID-19 patients selected at Saint-Luc University Hospital showed an average of 44% DAT positivity. In this population, the intensive care patients were more prone to DAT positivity than the general ward patients (statistically significant result). The positive DAT appeared « transmissible » to other RBCs via COVID-19 DAT-positive patient’s plasma. Conclusion: The strongest hypothesis explaining this observation is the targeting of cryptic antigens by autoantibodies in COVID-19 patients.

In this article, we describe the case of a fifty-year-old patient with autoimmune hemolytic anemia (AIHA) with constitutional symptoms, jaundice, unquantified fever and progressive dyspnea. The patient had history of smoking and Hepatitis A and following a physical exam she was found in a regular condition, icteric but with no other further signs. Her laboratory tests revealed hemolytic anemia with a hemoglobin of 8.5 g/dL, an increase of total and indirect bilirubin, an elevated ferritin, a decreased transferrin and haptoglobin and a positive result for direct Coomb’s test. Considering this, an immune profile was ordered finding a negative result of ANAs and ENAs and a decrease of complement C3 and C4. The patient was diagnosed with AIHA and as an initial step a corticosteroid treatment was administrated however the patient showed no clinical nor chemical improvement. At her third day of hospitalization, she was unstable hemodynamically requiring transfer to Intensive Care Unit (ICU) to optimize management. After 24 hours on ICU, due to persistence of deterioration of the patient, it was decided to manage with erythropoietin (EPO). In the following days, the patient showed a rise in her hemoglobin and an overall improvement made possible the transfer to hospitalization service. The AIHA is an uncommon disease and is not the first option that comes to mind with these symptoms, currently there are not controlled studies to the treatment due to its complexity and the heterogeneity of the results. We strongly support the use of EPO in refractory cases of this pathology.

Immune cytopenias occur when the body produces antibodies that target specific hematopoietic cells, inducing extravascular antibody-mediated phagocytosis by monocyte-macrophages in the spleen and/or liver through activation of Fcγ Receptors (FcγRs). Immune cytopenias include Immune Thrombocytopenia (ITP), Autoimmune Hemolytic Anemia (AIHA), Hemolytic Transfusion Reactions (HTR), Hemolytic Disease of the Fetus and Newborn (HDFN), and Autoimmune Neutropenia (AIN). Thus, novel therapeutics that inhibit phagocytosis would be useful, especially for short-term use while other therapies are being evaluated. In our earlier studies, we successfully identified two small-molecule drugs able to inhibit in vitro phagocytosis with a low IC50 concentration and negligible toxicity. These drugs, known as KB-151 and KB-208, have the potential to be utilized as lead compounds for further studies, once their mechanism of action is more clearly understood. In this regard, we have developed preliminary results that suggest that these small molecules may bind to the Fc receptors on monocyte macrophages and block the subsequent attachment of antibody-opsonized red blood cells to prevent phagocytosis.