Clinical significance of anti-Jra : report of two cases and review of the literature

BACKGROUND: Jr a is a high-frequency antigen seen in all populations, but the clinical significance of Jr a antibodies is incompletely understood. Two cases are reported in which patients with anti-Jr a received incompatible transfusions. CASE REPORTS: A 69-year-old Japanese man had anti-K and anti-Jr a . Despite multiple transfusions of Jr(a+), K- RBCs, his clinical course remained stable without evidence of hemolysis. A 45-year-old Japanese woman with anti-Jra was transfused with two units of Jr(a+) RBCs without clinical evidence of hemolysis. However, the same patient received an additional unit of Jr(a+) RBCs 1 week after the initial transfusions and, within 6 hours of transfusion, developed signs and symptoms of an acute hemolytic transfusion reaction. STUDY DESIGN AND METHODS: Routine serologic methods were used to study the patients' RBCs and plasma. A monocyte monolayer assay (MMA) was used to determine the potential clinical significance of the anti-Jr a , where reactivity (R) greater than 5 percent indicates potential clinical significance. RESULTS: The anti-Jr a in the first case had a pretransfusion titer of 32 with a MMA result of 3.3 percent R. No clinical or laboratory evidence of hemolysis was seen after transfusion of 4 units of Jr(a+), K- RBCs. The anti-Jra in the second case had a pretransfusion titer of 32 with a MMA result of 24.5 percent R. This patient developed an acute hemolytic reaction after transfusion of Jr(a+) RBCs. CONCLUSION: Anti-Jra can be clinically significant as demonstrated by acute hemolysis in the second case. The MMA accurately predicted the clinical outcome of each case and appears to be a useful tool in predicting the biologic behavior of anti-Jr a .