Veterinary Immunology and Immunopathology 147 (2012) 25–34 Contents lists available at SciVerse ScienceDirect Veterinary Immunology and Immunopathology j ourna l ho me pag e: www.elsevier.com/locate/vetimm Research paper Immunophenotyping and characterization of BNP colostra revealed pathogenic alloantibodies of IgG1 subclass with specifity to platelets, granulocytes and monocytes of all maturation stages Aryan Assad a , Barbara Amann b , Annette Friedrich a , Cornelia Annette Deeg b,∗ a Clinic for Ruminants, Centre of Clinical Veterinary Medicine, Ludwig-Maximilians University, Sonnenstraße 16, D-85764 Oberschleißheim, Germany b Institute for Animal Physiology, Department of Veterinary Sciences, Ludwig-Maximilians University, Veterinärstraße 13, D-80539 München, Germany a r t i c l e i n f o Article history: Received 11 January 2012 Accepted 10 April 2012 Keywords: Bovine neonatal pancytopenia Colostrum IgG1 alloantibodies Subclass Platelets Myeloid lineage a b s t r a c t Bovine neonatal pancytopenia (BNP) is mainly characterized by multiple haemorrhages, thrombocytopenia and leukocytopenia as a result of bone marrow depletion. BNP can be induced in healthy calves through application of colostrum from BNP donors, proofing that BNP is mediated to maternal alloantibodies. Alloantibody binding to bovine blood cells is present in sera and colostra of BNP donors and is probably initialized by vaccination with a certain BVD vaccine. To understand etiology and pathomechanisms of BNP, we closely characterized disease inducing antibodies regarding immunoglobulin subclass and binding specificities to peripheral blood derived leukocytes and platelets. By exact phenotyping the targeted blood cell subsets, including platelets for the first time, we investigated that BNP alloantibodies are exclusively of IgG1 subclass. Interestingly, IgG1 of BNP colostra bound to 70% leukocytes and 100% platelets irrespective of different bovine breeds and cellular maturity of all specimens tested. Furthermore, staining pattern on platelets as well as leuko- cyte subsets by BNP-IgG1 alloantibody exposed 100% reactivity to platelets, granulocytes and monocytes. Interestingly, the main part of T-helper cells was not bound by colostral alloantibodies. Our results point to a crucial role of IgG1 antibodies in BNP and to a target antigen that is expressed by all cells of myeloid lineage, but only partially by the lymphoid lineage. © 2012 Elsevier B.V. All rights reserved. 1. Introduction First seen in 2007 (Friedrich et al., 2009), bovine neona- tal pancytopenia (BNP) affects neonatal calves under four weeks of age from different breeds and gender. It is char- acterized by high susceptibility to internal or external bleeding due to severe pancytopenia and bone mar- row depletion leading to a high mortality rate (Friedrich ∗ Corresponding author. Tel.: +49 8921801630; fax: +49 8921802554. E-mail addresses: a.assad@tiph.vetmed.uni-muenchen.de (A. Assad), baerbl.amann@tiph.vetmed.uni-muenchen.de (B. Amann), a.friedrich@lmu.de (A. Friedrich), deeg@tiph.vetmed.uni-muenchen.de (C.A. Deeg). et al., 2009; Kappe et al., 2010; Pardon et al., 2009). In the initial phase, haematology shows leukocytopenia and thrombocytopenia (Friedrich et al., 2009; Pardon et al., 2009). Although infection with bovine viral diarrhoea virus (BVDV) can cause similar clinical symptoms, no BVD viral antigen was isolated in affected calves (Bell et al., 2010). Several other infectious agents (e.g. parvovirus, porcine cir- covirus type 2 and bluetongue virus) were ruled out as well (Friedrich et al., 2009; Kappe et al., 2010; Pardon et al., 2009). BNP was recently proven to be mediated by transfer of colostrum derived alloantibodies developed by BNP donor cows. BNP can experimentally be induced in unrelated calves through ingestion of colostrum from BNP donor dams (Friedrich et al., 2011; Schroter et al., 2011). These 0165-2427/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.vetimm.2012.04.012