Growing evidence suggests that ABO blood group may play a role in the immunopathogenesis of SARS‐CoV‐2 infection, with group O individuals less likely to test positive and group A conferring a higher susceptibility to infection and propensity to severe disease. The level of evidence supporting an association between ABO type and SARS‐CoV‐2/COVID‐19 ranges from small observational studies, to genome‐wide‐association‐analyses and country‐level meta‐regression analyses. ABO blood group antigens are oligosaccharides expressed on red cells and other tissues (notably endothelium). There are several hypotheses to explain the differences in SARS‐CoV‐2 infection by ABO type. For example, anti‐A and/or anti‐B antibodies (e.g. present in group O individuals) could bind to corresponding antigens on the viral envelope and contribute to viral neutralization, thereby preventing target cell infection. The SARS‐CoV‐2 virus and SARS‐CoV spike (S) proteins may be bound by anti‐A isoagglutinins (e.g. present in group O and group B individuals), which may block interactions between virus and angiotensin‐converting‐enzyme‐2‐receptor, thereby preventing entry into lung epithelial cells. ABO type‐associated variations in angiotensin‐converting enzyme‐1 activity and levels of von Willebrand factor (VWF) and factor VIII could also influence adverse outcomes, notably in group A individuals who express high VWF levels. In conclusion, group O may be associated with a lower risk of SARS‐CoV‐2 infection and group A may be associated with a higher risk of SARS‐CoV‐2 infection along with severe disease. However, prospective and mechanistic studies are needed to verify several of the proposed associations. Based on the strength of available studies, there are insufficient data for guiding policy in this regard.

Background: The development of anti-red blood cell antibodies (both allo-and autoantibodies) remains a major problem in thalassemia major patients. We studied the frequency of red blood cell (RBC) alloimmunization and autoimmunization among thalassemia patients who received regular transfusions at our center and analyzed the factors, which may be responsible for development of these antibodies. Materials and Methods: The study was carried out on 319 multiply transfused patients with β-thalassemia major registered with thalassemia clinic at our institute. Clinical and transfusion records of all the patients were examined for age of patients, age at initiation of transfusion therapy, total number of blood units transfused, transfusion interval, status of splenectomy or other interventions. Alloantibody screening and identification was done using three cell and 11 cell panel (Diapanel, Bio-rad, Switzerland) respectively. To detect autoantibodies, autocontrol was carried out using polyspecific coombs (IgG + C3d) gel cards. Results: Eighteen patients out of total 319 patients (5.64%) developed alloantibodies and 90 (28.2%) developed autoantibodies. Nine out of 18 patients with alloantibodies also had autoantibodies. Age at first transfusion was significantly higher in alloimmunized than non-immunized patients (P = 0.042). Out of 23 alloantibodies, 52.17% belonged to Rh blood group system (Anti-E = 17%, Anti D = 13%, Anti-C = 13%, Anti-C ^w = 9%), 35% belonged to Kell blood group system, 9% of Kidd and 4% of Xg blood group system. Conclusion: Alloimmunization was detected in 5.64% of multitransfused thalassemia patients. Rh and Kell blood group system antibodies accounted for more than 80% of alloantibodies. This study re-emphasizes the need for RBC antigen typing before first transfusion and issue of antigen matched blood (at least for Rh and Kell antigen). Early institution of transfusion therapy after diagnosis is another means of decreasing alloimmunization.

Extracorporeal photochemotherapy (ECP) is considered as an immune modulating therapy majorly targeting the T cells of the Immune system. ECP induces an anti-inflammatory condition with tolerogenic responses without inducing a global immunosuppression state which is a typical feature of other therapeutic options such as steroids. Clinical indication of ECP has grown over time since its initial applications. Our review discusses the technical aspects of the concept of photopheresis with the available methods for its clinical applications.