Douglas P. Blackall

The Gerbich (Ge) antigens are a collection of high-incidence antigens carried on the red blood cell membrane glycoproteins, glycophorins C and D. Antibodies against these antigens are uncommon, and there have been only rare case reports of hemolytic disease of the fetus and newborn due to anti-Ge. In this case report, we present a neonate with severe anemia and hyperbilirubinemia due to anti-Ge3. Routine and special laboratory studies undertaken in this case suggested two mechanisms for the patient's hemolysis and persistent anemia. Antibody-dependent hemolysis was associated with early-onset hyperbilirubinemia, anemia, and a mild reticulocytosis, and inhibition of erythroid progenitor cell growth was associated with late anemia and normal bilirubin and reticulocyte values. Though rare, anti-Ge3 can be a dangerous antibody in pregnancy. Affected neonates may require intensive initial therapy and close follow-up for at least several weeks after delivery.

Infliximab (Remicade) is a humanized mouse monoclonal antibody that blocks tumor necrosis factor α.¹ It down-regulates type 1 helper T-cell (Th1) immune responses and increases type 2 helper T-cell (Th2) responses, thereby favoring antibody production.² There are many reports of autoantibody formation after the administration of infliximab, including a case of autoimmune hemolytic anemia.¹ We report on a 10-month-old boy who received infliximab for systemic-onset juvenile rheumatoid arthritis and who had a severe hemolytic transfusion reaction.

The significance of warm-reactive autoantibodies in pediatric patients has not been a subject of thorough evaluation. This study was undertaken to correlate the clinical and serologic features of these antibodies to identify predictors of clinical significance. Forty-two consecutive patients with serologically detectable warm-reactive autoantibodies were studied. These patients (21 male, 21 female) had a mean age of 9 years (range: 2 mo to 21 y). Primary diagnoses included autoimmune disorders (14), sickle cell disease (14), viral infection (4), idiopathic autoimmune hemolytic anemia (2), leukemia (2), and other diseases (6). Autoimmune hemolysis, as determined by clinical and laboratory findings, was documented in 24 patients (57%). Serologic studies revealed that all patients demonstrated IgG on their red cells [Direct Antiglobulin Test (DAT) reactivity range: microscopic to 3+]; 17 (40%) also demonstrated complement (DAT reactivity range: microscopic to 2+). There was a correlation between the strength of the DAT for IgG and the presence of complement on the red cells, with both being important predictors of hemolysis. These findings may be useful in predicting the clinical significance of warm-reactive autoantibodies in pediatric patients and allow for more efficient and effective follow-up care.

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‐Jr^a 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‐Jr^a 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‐Jr^a 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.