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Increases in cerebrospinal fluid (CSF) levels of the acute phase protein haptoglobin (Hp) occur in central nervous system (CNS) disorders such as Alzheimer's disease. To establish if Hp CSF level increases can be associated with Hp expression in brain, reverse transcription-polymerase chain reaction (RT-PCR) experiments were conducted to determine if the Hp mRNA transcript is expressed in human glioblastoma cells. Furthermore, Western blots and immunoprecipitations were performed to elucidate if Hp protein is synthesized and secreted by human glioblastoma cells. The Hp mRNA (alpha2beta) transcript (1155 bp) was detected both in U-87MG and U-138MG cells, and was positively verified by nested PCR in which a part of the beta sequence (482 bp) was targeted for amplification. Despite the presence of Hp mRNA, Hp protein was not secreted by U-87MG cells as compared to the hepatoma cell line, HepG2, where Hp protein (approximately 46 kDa) was detected in the media. The results suggest the expression of Hp protein by glioblastoma cells is possible since the Hp mRNA transcript exist, but whether or not Hp mRNA is contained in a storage pool requiring a specific signal for translation or is transiently expressed remains to be uncovered in future studies.

Transgenic mice carrying the three common human apolipoprotein E (APOE) alleles have been developed. In this study, brains of the transgenic mice have been analyzed by in situ histohybridization, immunohistochemistry, and immunoblots to determine sites of gene expression, to identify specific brain cells associated with human apoE protein, and to determine the relative concentrations of the human apoE. Results indicate that (1) human APOE mRNA and apoE protein occur in the gray and white matter of transgenic mouse brains; (2) in the hippocampus of transgenic brains, human apoE protein reacts immunologically within the same cells as the glial fibrillary acidic protein (GFAP), a specific marker for astrocytes; and (3) concentrations of the apoE isoforms determined in three heterozygous transgenic brains range from 22 to 250 pmol/g wet weight of brain.