Prevalence and laboratorial determinants of the clinical relevance of antibodies of undetermined specificity

Abstract

Background and Objectives Antibodies of unknown specificity (AUS) are frequently identified in the pre‐transfusion testing. These antibodies can be insignificant or potentially cause post‐transfusion haemolysis. Information about the prevalence of clinically relevant AUS is still lacking. Our aim was to predict the potential clinical relevance of AUS using the monocyte monolayer assay (MMA) and to identify the clinical and laboratorial determinants of AUS’ significance. Materials and Methods Antibodies of unknown specificity identified at a single institution from 2015–2017 were evaluated through MMA. A monocyte index (MI) of more than 5% was predictive of potential post‐transfusion haemolysis. Results Thirty‐two patients with AUS were included in the study. Of the studied AUS, 37·5% (12/32) presented with a monocyte index (MI) more than 5%. In the group of significant AUS, 41·7% of the patients presented with sickle cell disease (SCD) and the AUS were associated with Rh antibodies in 75% of the cases. In the group of insignificant AUS, only 10% of the patients had SCD and the association with Rh antibodies was detected in 20% of the cases. The presence of Rh antibodies was independently associated with the AUS clinical relevance (P = 0·012). Conclusion More than one‐third of the AUS are potentially clinically relevant, and the association with Rh antibodies is predictive of AUS relevance. Services must honour AUS in the pre‐transfusion process in order to ensure transfusion safety.

The impact of an antibody investigation algorithm emphasizing specificity on reducing potential false‐positive warm autoantibody detection at a Canadian tertiary care centre

“…We chose the term AUS or ‘antibody of undetermined significance’ instead of ‘antibody of unknown specificity’, which was described in the literature aiming to capture only non‐specific reactions that appeared panreactive and were most likely not associated with haemolysis risk [4, 18, 19]. Our aim was to eliminate non‐specific solid‐phase reactions frequently regarded as likely clinically insignificant.…”

Serologic reactivity of unidentified specificity in antenatal testing and hemolytic disease of the fetus and newborn: The BEST collaborative study

“…The indication for treatment with phototherapy was not provided. In another study, 12/32 (37.5%) of patients with SRUS demonstrated a monocyte index of >5% by monocyte monolayer assay 4 . While an in vitro result, this finding raises concern that SRUS may be clinically significant.…”

“…In another study, 12/32 (37.5%) of patients with SRUS demonstrated a monocyte index of >5% by monocyte monolayer assay. 4 While an in vitro result, this finding raises concern that SRUS may be clinically significant. Furthermore, SRUS may precede the identification of a clinically significant antibody at a later timepoint.…”