A second example of autoanti‐Jk3

To the Editor: In 1982, Ellisor et al.' reported the first example of autoanti-Jk3; this report describes the second. A 3 I-year-old white woman (para 1, gravida 2) in her first trimester was diagnosed as having thrombotic thrombocytopenic purpura. Her red cells typed as group A', Rh-positive. At the time of her first admission no unexpected antibodies were present in her serum. Over a period of 20 days, she received 3 units each of packed red cells and freshfrozen plasma and 24 single-unit platelet concentrates. No further transfusions were given. Five months later she was seen at another hospital for prenatal screening, and her blood was sent to a reference laboratory. Anti-I, -Lea, and -Leb were identified in her serum in tests at room temperature; prewarmed tests showed anti-Jkb reactive at 37" C with monospecific anti-IgG human globulin. No other blood group antibodies were detected. The direct antiglobulin test (DAT) was 24using anti-IgG. Acid and dichloromethane (DCM) eluates prepared from her red cells reacted 2+ in anti-human globulin with all panel cells, 2 aminoethylisothiouronium bromide (AET)-treated cells, and an RhnUll sample. However, the eluates did not react with 14 examples of Jk(a-b-) rgd cells in IATs using untreated and ficin-treated cells. A single absorption of the DCM eluate with Jk(a+b-) or Jga-b+) red cells removed all antibody, but asingle absorption with Jk(a-b-) red cells left antibody activity unaffeeted. The proposita's red cells were treated with dithiothreitol/ papain mixture (ZZAP) and then typed as Jk(a+b-), Jk:3. Her ZZAP-treated and untreated red cellsdid not adsorb anti-Jkb. Her untreated red cells were hemolyfed by incubation with 2 A4 urea. Control Jk(a-b-) red cells resisted such hemolysis. Six weeks later the proposita delivered a boy at term. The infant typed as group A, Rh-positive and had a I + DATdue to IgQ. The cord serum reacted weakly with Jk(b+) red cells. A DCM eluate prepared from the cord red cells contained only anti-Jkb. ZZAP-treated cord blood red cells typed as Jk(a+b+), Jk:3. The total bilirubin level was 2.2 mg per dl on the cord blood sample; it reached a peak of 7.1 mg per dl on the second day of the infant's life. A paternal blood sample was not available for phenotyping. This is the second case report that documents an autoantibody with apparent anti-Jk3 specificity that was detected during pregnancy. Neither infant showed significant red cell hemolysis attributable to the maternal autoantibody. In this case, the anti-Jkb eluted from the cord blood red cells was apparently an alloantibody made by the mother in addition to her autoanti-Jk3. Although alloanti-Jk3 has caused mild HDN in some it was not observed with autoanti-Jk3 in the two cases reported. TERRENCE O'DAY, MA, MT(ASCP) SBB American Red Cross Blood Services Central California Region 333 McKendrie Street San Jose, CA 95110