Hilmar Prange

Serum tau protein level as a marker of axonal damage in acute ischemic stroke.

Biochemical markers of brain damage, e.g. ischemic stroke, should reflect the volume of irreversibly damaged brain parenchyma and the clinical outcome in a single patient in order to allow estimation of prognosis at an early stage. Tau protein, which derives predominantly from neurons and axons, is elevated in the cerebrospinal fluid of patients with neurodegenerative disease. This makes tau protein a potential marker of neuronal/axonal injury. In order to test this hypothesis, the current study aimed at showing that tau protein is measurable in the blood after acute ischemic stroke and that it correlates with clinical disability and stroke volume. In a longitudinal prospective study we measured tau protein serum levels with an ELISA in 30 patients longitudinally after ischemic stroke. Tau protein was detectable within 5 days after ischemia in the sera of 7/20 patients with MRI-proven infarction and in 2/10 patients with transitory ischemic attack; both of them had a small infarction visible on the MRI scan. Tau protein was measurable within 6 h after symptom onset, peaked after 3–5 days and correlated with infarct volume and disability after 3 months. In conclusion, serum tau protein is a candidate marker of axonal injury. In stroke, its clinical use is limited, because it is detectable only in a proportion of patients.

Different binding pattern of antibodies to prion protein on lymphocytes from patients with sporadic Creutzfeldt-Jakob disease.

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.