Please cite this article in press as: Pardon, B., et al., Sera from dams of calves with bovine neonatal pancy- topenia contain alloimmune antibodies directed against calf leukocytes. Vet. Immunol. Immunopathol. (2011), doi:10.1016/j.vetimm.2011.02.017 ARTICLE IN PRESS G Model VETIMM-8472; No. of Pages 8 Veterinary Immunology and Immunopathology xxx (2011) xxx–xxx Contents lists available at ScienceDirect Veterinary Immunology and Immunopathology journal homepage: www.elsevier.com/locate/vetimm Short communication Sera from dams of calves with bovine neonatal pancytopenia contain alloimmune antibodies directed against calf leukocytes Bart Pardon a,∗ , Edith Stuyven b , Sabrina Stuyvaert a , Miel Hostens c , Jeroen Dewulf c , Bruno Maria Goddeeris b,d , Eric Cox b , Piet Deprez a a Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium b Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium c Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium d Departement of Biosystems, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 30, 3001 Heverlee, Belgium article info Article history: Received 1 October 2010 Received in revised form 14 February 2011 Accepted 22 February 2011 Keywords: Bovine neonatal pancytopenia Leukocytes Calves Antibodies Flow cytometry abstract Bovine neonatal pancytopenia (BNP) is a bleeding and pancytopenic syndrome in neonatal calves, which recently emerged all over Europe. The present study tested whether antibod- ies directed against calf leukocytes are present in sera from known BNP dams. Sera from BNP dams (n = 11) were combined with leukocytes from 11 calves (5 BNP survivors and 6 controls). After adding a fluorescein conjugated F(ab’) 2 fragment of rabbit anti-bovine IgG (H&L) the level of antibody binding was measured by flow cytometry. As control groups both sera from dams from BNP affected (n = 48) as from unaffected (n = 54) herds were combined with leukocytes from the same calves. With sera from BNP dams, antibody binding could be visualised by immunofluoresence in both peripheral blood as in bone marrow smears. Mean fluoresence intensity values of all leukocyte subpopulations were significantly higher for the BNP dams compared to both control groups (P < 0.01). BNP dams showed significantly more antibody binding on multiple leukocyte subpopulations of both BNP survivors and control calves and this from cut off values of MFI 100 onwards (P < 0.01). The BNP sur- vivor calves reacted significantly more often with sera from the BNP dams than the control calves (P < 0.01). In conclusion the present study supports the hypothesis that BNP is an immune-mediated disease. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Bovine neonatal pancytopenia (BNP) is the consensus name for a bleeding and pancytopenic syndrome in neona- tal calves, which emerged in 2008 all over Europe (Friedrich et al., 2009a; Pardon et al., 2010). BNP occurs in neonatal calves from different breeds and is characterized by exter- nal and internal bleeding. Haematology shows leukopenia, thrombocytopenia and anemia, with the latter at least partly influenced by the degree of bleeding. The main ∗ Corresponding author. Tel.: +32 9 2647590; fax: +32 264 7796. E-mail address: bart.pardon@ugent.be (B. Pardon). affected tissue is the bone marrow, which is completely aplastic in most fatal cases (Friedrich et al., 2009a; Kappe et al., 2010; Pardon et al., 2010). Survival of the disease occurred in approximately 10% of the clinical cases and also subclinical cases with pancytopenia but no obvious bleed- ing have been described (Friedrich et al., 2009a; Pardon et al., 2010). The etiology of BNP is currently unknown. Several attempts to isolate or detect an infectious agent, system- atically yielded negative results and the limited number of toxicological assays were negative as well (Friedrich et al., 2009a; Pardon et al., 2010; Kappe et al., 2010). Although circoviral DNA, highly similar to porcine cir- covirus type 2b, was detected in 5 of 25 BNP cases, there 0165-2427/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.vetimm.2011.02.017