In Creutzfeldt-Jakob disease (CJD), progressive neuronal cell death probably occurs as a result of a change in conformation of the physiological prion protein (PrP(C)). There is evidence of participation of the lymphatic system and in particular of lymphocytes in the intracorporeal transportation of the pathological prion protein (PrP(Sc)) in new variant CJD and scrapie. Using fluorescence cytometry, we investigated a possible alteration of PrP(C) on lymphocytes of patients with sporadic CJD. We demonstrated a significantly lower binding pattern of antibodies (3F4) against physiological prion protein to lymphocytes of patients with sporadic CJD (n=16) compared with control patients. In contrast this difference was not found on platelets (n=23). For the first time we were able to present a measurable difference of antibody binding on lymphocytes of patients with CJD. One interpretation of this finding is that lymphocytes patrolling the brain bind and transport PrP(Sc) which has a lower binding affinity for the antibodies directed against physiological PrP.