Some immunochemical aspects of HD-brain extracts

Cortical gray matter extracts of patients with Huntington's disease (HD) were investigated for their antigenic properties with serum from both HD patients and normal controls. Both patient and control sera appeared to precipitate two closely migrating proteins of MW 14.4K and 15K, which could be found in normal brain preparations only at much lower concentrations, as precipitation of these proteins could not effectively be inhibited by a concentrated "cold" normal brain extract. It is shown that these molecules are hemoglobin and lysozyme, which to a certain extent bind specifically to the immunoprecipitates. The increase in hemoglobin level, which amounted to about 20% of the total protein concentration, might be explained either as an epiphenomenon to the disease process, in which degeneration of the HD brain leads to a relative increase of the arterial and capillary blood system, or as an artifact due to the preparation of the brain extracts. The lysozomal increase is a feature shared by many degenerative neurological diseases. No measurable humoral reactivity could be demonstrated in patient sera against a presumed mutant HD-specific protein. In addition, using antisera to the viral structural protein p30, no evidence could be found for the involvement of a retrovirus in HD.