Effectiveness of a red cell antigen‐matching transfusion protocol in sickle cell disease patients

Abstract

Background and objectives To date, it is unclear whether antigen matching is effective in reducing antibody development and whether transfusing blood from non‐Caucasian donors reduces alloimmunization in sickle cell disease patients (SCP). This study was designed to evaluate the effectiveness of an antigen‐matching strategy supplied by a mixed donor population, in reducing alloimmunization in SCPs. Methods Eighty SCPs transfused with C‐, E‐ and K‐matched units and 2000 donors were genotyped for the most relevant RBC antigens, and resulting genotypic frequencies were compared. Also, alloantibodies specificity and clinical complications were evaluated in SCPs. Results A high alloimmunization rate was observed despite the prophylaxis protocol (62·1%). The main cause underlying lack of effectiveness was transfusion of non‐matched units in external hospitals. Even though our donor population was ethnically mixed, it still exhibited antigenic differences in relation to SCPs (C and Fya). Frequency of clinical complications was similar between alloimmunized and non‐alloimmunized patients. Conclusions Prospective antigen matching is an unattractive alloimmunization prophylaxis for SCPs if not associated with strategies to minimize the hazards related to transfusions at non‐index hospitals. Even in a highly mixed donor population, antigenic discrepancies in SCPs are high, increasing the risk of antibody development.

Optimized Antigen-Matched in Sickle Cell Disease Patients: Chances and Challenges in Molecular Times - the Brazilian Way

“…Even though prospective antigen-matched transfusions are a reality for many Brazilian transfusion centers which take care of SCD patients, the alloimmunization rates observed in our country are still above that described in the literature [7]. There are multiple factors underlying the higher risk of post-transfusion alloantibody formation observed among Brazilian SCD patients, some of them already depicted as potential pitfalls by multiple studies [24,25] and some reflecting the heterogeneity of transfusion and laboratory policies throughout the country.…”

“…We have recently studied 80 SCD patients who were under chronic transfusion treatment receiving level 1-matched transfusions [7]. The first surprising factor was that 46% of the individuals were already alloimmunized (mainly against Rh antigens) at the beginning of the antigen-matched transfusion protocol.…”

“…The presence of RH variants was detected in 32% of the Brazilian SCD patients who developed Rh alloantibodies, irrespective of receiving level 1-matched transfusions [7]. Recently, we have evaluated 35 SCD patients with unexplained Rh antibody, meaning they exhibited a certain Rh antibody in the sera but phenotyped as antigen-positive, using a NGS-based strategy in the Ion Torrent system (Thermo Fisher Scientific, Waltham, MA, USA) [27].…”

“…The incidence of alloimmunization in patients with SCD in Brazil ranges from 10 to 60% depending on the region and on the protocol of antigen matching used [4,5,6,7,8]. Even though our population is very mixed, we have observed that patients and donors exhibit differences in their genotype frequencies what could explain the high rates of alloimmunization in some regions [4,7].…”

“…Even though our population is very mixed, we have observed that patients and donors exhibit differences in their genotype frequencies what could explain the high rates of alloimmunization in some regions [4,7]. …”