Can therapeutically-rational exchange (T-REX) of type-O red blood cells (RBCs) benefit Plasmodium falciparum malaria patients?

ABO blood group antigens and differential glycan expression: Perspective on the evolution of common human enzyme deficiencies

Enzymes catalyze biochemical reactions and play critical roles in human health and disease. Enzyme variants and deficiencies can lead to variable expression of glycans, which can affect physiology, influence predilection for disease, and/or directly contribute to disease pathogenesis. Although certain well-characterized enzyme deficiencies result in overt disease, some of the most common enzyme deficiencies in humans form the basis of blood groups. These carbohydrate blood groups impact fundamental areas of clinical medicine, including the risk of infection and severity of infectious disease, bleeding risk, transfusion medicine, and tissue/organ transplantation. In this review, we examine the enzymes responsible for carbohydrate-based blood group antigen biosynthesis and their expression within the human population. We also consider the evolutionary selective pressures, e.g. malaria, that may account for the variation in carbohydrate structures and the implications of this biology for human disease.

ABO blood group should be considered and reported when red blood cell exchange transfusion is used to treat Plasmodiumfalciparum Malaria patients

Laboratory and epidemiologic studies have clarified how persons born with malaria-resistant red blood cells (RBCs)-like group-O, sickle-trait, and C-trait RBCs-are protected against death or severe disease due to Plasmodiumfalciparum (Pf) infection. Compared to malaria-promoting RBCs-like non-O or hemoglobin-AA RBCs-inborn RBC protection against severe Pf malaria can be profound: up to 10-fold greater. Given that "the Berlin patient" success showed patients do not have to be born with disease-resistant cells to benefit from them, why have the biologically plausible benefits of exchange transfusion (ET) of malaria-resistant RBCs not yet been evaluated? Unfortunately, a 2013 ET-for-malaria meta-analysis could not quantify the impact on mortality of ET of malaria-resistant RBCs because RBC malaria resistance variables (ABO group, hemoglobin type, enzyme levels, etc.) had not been reported in any of the ET studies used in that meta-analysis. To promote evaluation of the therapeutic impact of specific malaria-resistant RBCs, we urge clinicians to always report ABO blood group (and all other RBC malaria-resistance variables they are aware of) when they use ET to rescue Pf-infected patients. Prudent selection of donor RBCs has successfully optimized ET for sickle cell disease patients, and this precedent suggests selection of special malaria-resistant donor RBCs may optimize ET for Pf-malaria patients. Given that ET is used worldwide as a rescue adjunct, we feel it is most prudent to now assume-until proven otherwise-that considering and reporting the Pf-malaria-resistance variables of the RBCs to be transfused-at least ABO status-will help optimize ET-for-malaria.