Acute haemolytic transfusion reactions due to weak antibodies that in vitro did not seem to be clinically significant

Abstract

Weak alloantibodies that in vitro do not seem to be clinically significant may cause severe AHTRs.

The molecular diversity of Sema7A, the semaphorin that carries the JMH blood group antigens

“…All blood samples were obtained with the informed consent of the patients, and the trial protocol was approved by the local ethics committee of the Hanover Medical School. Samples from some individuals with unusual JMH expression had been assessed in previous serologic studies 17,19,21 . In all cases, genomic DNA was derived from peripheral blood cells with a DNA purification kit (QIAamp DNA blood mini kit, Qiagen, Hilden, Germany).…”

“…In contrast, the inherited phenotype is characterized by alloantibodies that do not react with JMH‐negative cells or the RBCs of some of the patients' siblings. There is some evidence suggesting that antibodies of this very rare phenotype may be clinically relevant 17,18 . In the only family in which a JMH‐negative phenotype was shown to be inherited, absence of the JMH antigen appeared in three generations, suggesting autosomal dominant inheritance of the phenotype 19…”

Rapid detection of JMH antibodies with recombinant Sema7A (CD108) protein and the particle gel immunoassay

“…The inherited phenotype is characterized by amino acid variations in the Sema7A protein and can be alloimmunized against missing epitopes. There is some evidence suggesting that antibodies of this very rare phenotype may be clinically relevant 4,5 . Because no JMH‐negative test cells are commercially available, JMH antibody detection relies on blood samples from donors and patients known to be JMH‐negative.…”

JMH Blood Group System

“…One such patient received 20 units of JMH + blood in 10 months, with the expected haemoglobin rise [20] . One JMH antibody is reported to have caused an acute intravascular HTR, but evidence that the JMH antibody was responsible for the reaction is limited [22] . One JMH antibody is reported to have caused an acute intravascular HTR, but evidence that the JMH antibody was responsible for the reaction is limited [22] .…”