[Alzheimer disease: involvement of the complement system in cell death. Gene expression of C1q and C3 in the frontal cortex of patients with Alzheimer disease and control probands].

Patients with Alzheimer's disease are found to have inflammatory changes in the vicinity of plaques and fibrils, and involvement of the complement system has been confirmed by immunocytochemical studies. In order to confirm these findings on the genetic plane, the prevalence of mRNAs for C1q and C3 complement components were investigated in our laboratory. We were able to show that the hybridization signals for complement C1q-mRNA on Northern blots of deceased Alzheimer patients were about 3.5 times as pronounced as in the case of control persons. In contrast to earlier reports, no difference in the expression of complement C3-mRNA in the brains of decreased Alzheimer patients and control persons was established. On the other hand, with the aid of non-radioactive in situ hybridization with digoxigenin-labelled riboprobes, it has been shown that complement C1q- and C3-mRNA is closely associated with the neurons.