Passenger lymphocyte syndrome after solid organ transplantation: Laboratory perspective

Passenger lymphocyte syndrome (PLS) is an uncommon cause of post-transplant hemolysis, typically associated with minor ABO or RhD incompatibility between donor and recipient. Despite being self-limiting in most cases, PLS can complicate transfusion support and is often underrecognized in clinical practice METHODS: We retrospectively reviewed cases of PLS identified at a tertiary care hospital between January 2012 and December 2021. Case identification was based on donor-recipient minor ABO or RhD incompatibility, a newly positive direct antiglobulin test and/or detection of donor-derived alloantibodies, unexplained incompatible crossmatch results, and exclusion of other causes of hemolysis. Clinical and laboratory findings, transfusion history, and duration of antibody persistence were analyzed RESULTS: A total of 11 cases were identified: nine liver, one kidney, and one lung transplant. All occurred shortly after ABO- or RhD-minor incompatible transplantation in recipients requiring transfusion for anemia. Donor blood groups were predominantly group O, Rh positive. DAT positivity appeared within the first few days, most commonly with IgG specificity, and resolved within 9-21 days in most patients, with one case persisting until day 37.

Our findings highlight that PLS can be detected primarily from the blood bank. laboratory perspective, often in the absence of overt clinical suspicion. Active. communication and information sharing between clinical teams and laboratories. remain essential for timely recognition and appropriate management of this condition.