Lemay Anne-Sophie, Tong Tik Nga, Branch Donald R, Huang Mary, Sumner Christopher, Oldfield Lynne, Hawes Janice, Cserti-Gazdewich Christine M, Lau Wendy
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
the Centre for Innovation, Toronto, Ontario, Canada.
Transfusion. 2018 Nov;58(11):2506-2512. doi: 10.1111/trf.14867. Epub 2018 Oct 9.
Alloantibodies to the low-frequency antigen Scianna-2 (Sc2) have been implicated in cases of hemolytic disease of the fetus and newborn but never in hemolytic transfusion reactions (HTRs); thus, the clinical significance of anti-Sc2 has yet to be fully addressed.
A 26-year-old woman with thalassemia presented rigors, fever, nausea, abdominal pain, and hemolytic biochemistry after exposure to 75 mL of plasma-reduced red blood cells (RBCs). The RBC unit was issued by electronic crossmatch but was 3+ incompatible on recrossmatch by gel indirect antiglobulin test (IAT). The patient had anti-Sc2 previously identified, but considered to be clinically insignificant. The transfusion history was reviewed and a monocyte monolayer assay (MMA) was performed.
The patient was investigated for a RBC reaction 9 years prior, when she developed symptoms of HTR. The RBC unit was crossmatched by immediate spin due to consistent screen negativity. Full crossmatch found the RBC 1+ incompatible by gel IAT with both pre/post samples, while direct antiglobulin test was negative (pre) and 1+ immunoglobulin G positive (post). The antibody remained unidentified and she was committed to gel IAT crossmatch. Two-years later, the specificity to Sc2 was deduced when one RBC unit was found 3+ incompatible. Finally, the transfusion reaction reported herein occurred when she received by happenstance RBCs from the same donor who was associated with the remote reaction 9 years earlier. MMA yielded highly positive phagocytic indices only for Sc2+ RBCs, including the donor's RBCs that triggered the severe HTR.
This is the first case of HTR caused by anti-Sc2 confirmed by clinical findings and MMA.
针对低频抗原斯恰纳-2（Sc2）的同种抗体已被认为与胎儿及新生儿溶血病有关，但从未与溶血性输血反应（HTR）相关；因此，抗Sc2的临床意义尚未得到充分阐明。
一名26岁的地中海贫血女性在输注75毫升去血浆红细胞（RBC）后出现寒战、发热、恶心、腹痛及溶血性生化指标异常。该RBC单位通过电子交叉配血发出，但在凝胶间接抗球蛋白试验（IAT）复查交叉配血时出现3+不相合。患者之前已鉴定出抗Sc2，但认为其临床意义不大。回顾了输血史并进行了单核细胞单层试验（MMA）。
该患者9年前曾因出现HTR症状而接受RBC反应调查。由于筛查结果始终为阴性，RBC单位通过立即离心进行交叉配血。完全交叉配血发现，凝胶IAT显示RBC与前后两份样本均为1+不相合，而直接抗球蛋白试验术前为阴性，术后为1+免疫球蛋白G阳性。抗体仍未明确，她一直采用凝胶IAT交叉配血。两年后，当发现一个RBC单位为3+不相合时，推断出其对Sc2具有特异性。最后，本文报道的输血反应发生在她偶然接受了来自9年前那次远期反应相关同一供者的RBC时。MMA仅对Sc2+ RBC产生高度阳性的吞噬指数，包括引发严重HTR的供者RBC。
这是首例经临床发现和MMA证实由抗Sc2引起的HTR病例。
