117 Vox Sanguinis (2001) 80, 117–120 CASE REPORT © 2001 Blackwell Science Blackwell Science, Ltd Treatment with plasmapheresis and intravenous immunoglobulin in pregnancies complicated with anti-PP 1 P k or anti-K immunization: a report of two patients M. C. Fernández-Jiménez 1 , M. T. Jiménez-Marco 1 , D. Hernández 1 , A. González 2 , F. Omeñaca 3 & C. de la Cámara 1 1 Department of Hematology and Hemotherapy, Hospital La Paz, Universidad Autónoma de Madrid, Madrid, Spain 2 Department of Obstetrics and Gynecology, Hospital La Paz, Universidad Autónoma de Madrid, Madrid, Spain 3 Department of Neonatology, Hospital La Paz, Universidad Autónoma de Madrid, Madrid, Spain Background and Objectives In addition to anti-D alloantibody, other antibodies such as anti-K antibody and anti-PP 1 P k antibody have been reported to cause severe haemolytic disease of the newborn (HDN). HDN caused by anti-K results not only from destruction of red cells but also from suppression of erythropoiesis. Anti-PP 1 P k has been associated with abortion early in pregnancy. We report on two patients, one with anti-PP 1 P k and the other with anti-K, who were treated with plasmapheresis and intravenous immunoglobulin (IVIG) during pregnancy in an attempt to reduce the plasma antibody levels. Materials and Methods The patient with anti-PP 1 P k had lost all seven previous fetuses in the first trimester and therefore therapy in this patient was started at 8 weeks of gestation. The second patient had been sensitized to the K antigen through blood transfusion and had had two intrauterine fetal deaths at 26 weeks of gestation with signs of hydrops fetalis. Treatment in this patient was started during the 16th week of pregnancy. Results As a result of therapy, the antibody titre was reduced in both patients. In the first patient a healthy infant was delivered by Caesarean section at 37 weeks of gestation. The second patient gave birth at 36 weeks of gestation. Neither newborn required exchange transfusion. Conclusions In our two patients, plasmapheresis combined with IVIG proved success- ful in the management of fetomaternal incompatibilities where the mechanism of fetal loss differs from the classical anti-D. Key words: anti-PP 1 P k , haemolytic disease of the newborn, Kell alloimmunization, plasmapheresis, pregnancy. Received: 23 February 2000, revised 19 October 2000, accepted 9 November 2000 Introduction Rh D immunization is the prototype of maternal allo- immunization and haemolytic disease of the newborn (HDN). Several antibodies with specificities other than anti-D have been reported to cause severe HDN. The mechanism of fetal harm mediated by anti-K antibody and by anti-PP 1 P k antibody differs from the classical HDN associated with anti-D alloantibodies. In the case of anti-K, an inhibition of erythroid progenitor cell growth [1] contributes significantly to the anaemia, in contrast to anti-D HDN where the anaemia is primarily caused by antibody-mediated destruc- tion of red cells. Anti-PP 1 P k has been associated with abortion early in pregnancy [2–5], probably through a cytotoxic effect on the placenta and developing fetal tissues [6]. Correspondence: M. Cristina Fernández-Jiménez, Santa Engracia 48, 2 C, 28010 Madrid, Spain Tel.: +34-91-727-7116 Fax: +34-91-446-2797 E-mail: fdezjnez@teleline.es