Updated project metadata. A new vaccine against bovine viral diarrhea (BVD) induced unwanted immune reactions with production of alloreactive antibodies in 5–10% of vaccinated cows. Transfer of these antibodies via colostrum caused bovine neonatal pancytopenia (BNP) in calves, with a lethality rate of 90%. The exact immunological mechanisms behind the onset of BNP are not fully understood to date, however, an immune deviant phenotype of immune cells is assumed. To gain deeper insight into disease onset and pathogenesis, we analyzed the lymphocyte (PBL) proteome from alloreactive antibody producers (BNP cows) and non-responders (controls) after stimulation with PWM.