Anti-LAN Antibodies: Clinical Implications and Case Presentation

Abstract Introduction/Objective The LAN system, originating from the 901 Series of High Incidence antigens, transitioned to a recognized System in 2012. The LAN antigen, situated on ABCB6, a multipass membrane protein associated with porphyrin transport, plays a crucial role in heme synthesis. Functionally, LAN acts as an ATP-binding cassette transporter on the red blood cell membrane. Comprising a single antigen, LAN exhibits elevated expression in various tissues including the heart, skeletal muscles, fetal liver, mitochondrial membrane, eye, and Golgi apparatus. Notably, LAN shows no specific association with any particular geographic or ethnic group. Resistant to Ficin/Papain, Trypsin, α-Chymotrypsin, and 0.2M DTT, LAN antibodies primarily consist of IgG and necessitate IAT for detection. While Anti-LAN has been implicated in Hemolytic Transfusion Reactions (HTRs), its involvement in Hemolytic Disease of the Fetus and Newborn (HDFN) remains infrequent. LAN-negative blood is exceedingly rare, often requiring Monocyte Monolayer Assay Testing (MMA) for clinical assessment. Methods/Case Report Case Presentation: An 81-year-old female with a medical history including seizure disorder, hypertension (HTN), hyperlipidemia (HLD), gastroesophageal reflux disease (GERD), small bowel obstruction, and high-grade de-differentiated metastatic retroperitoneal liposarcoma presented for preoperative evaluation. A type and screen ordered as part of outpatient preoperative assessments revealed a positive antibody screen. Further investigation traced the origin of the anti-LAN antibody to an external facility since 2017. Antibody identification indicated the reactivity of the patient’s plasma with all cells (1+ AHG in PEG), excluding the auto control. Utilizing rare frozen antisera anti-LAN, the patient was phenotyped for LAN, yielding a LAN-negative status. Subsequent testing with three rare frozen LAN-negative group O cells aimed to exclude clinically significant antibodies. Differential adsorption, employing a comprehensive baseline RBC phenotype record obtained from the external facility, ruled out anti-E, anti-K, and anti-Fyb, thereby confirming Anti-LAN specificity. Results (if a Case Study enter NA) NA Conclusion The exceptional rarity of LAN-negative blood underscores the high prevalence of reactivity to Anti-LAN antibodies, exceeding 99% in most populations. In select cases, autologous transfusion may emerge as a viable management strategy. Consequently, the patient’s surgical procedure has been deferred, with no immediate requirement for blood products.