Date of Award:

5-1-1994

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Biology (Molecular Biology)

Committee Chair(s)

Vijendra K. Singh

Committee

Vijendra K. Singh

Committee

Joseph K.-K. Li

Committee

Jon Y. Takemoto

Committee

Reed P. Warren

Abstract

Brain S100 protein (S100), a Ca2+-binding protein, may be involved in the pathogenesis of certain neurodegenerative diseases. Nervous and immune systems have recently been shown to express common proteins. Therefore, this research investigated the hypothesis that S100 is present in immunocytes, the cells of the immune system. For the detection of S100, three techniques were used: enzyme-linked immunoassay (EIA), protein-immunoblotting (PIB), and two-dimensional gel electrophoresis (2D-gels). By using rabbit antibodies to bovine brain S100 protein (R⍺BS100), immunoreactive proteins were detected in immunocytes isolated from the peripheral blood of normal donors. Antigens were found in lymphocytes, but not in monocytes. The immunocyte antigen was slightly larger (12-14 kD) than bovine brain S100 (10.5 kD). By using PIB, the immunocyte protein was compared with S100 extracted from human brain, mouse brain, and human astrocytoma (U373) cells. Immunocytes contained mainly a low molecular weight (12-14 kD) immunoreactive protein whereas the brain cells contained mainly a high molecular weight protein (60-75 kD); these brain samples but not U373 cells also contained low molecular weight (10.5 kD) immunoreactive protein. From 2D-gel analysis it was evident that immunocyte S100 protein has a pl of 7.28 as compared to the pl of pure brain protein that was 5.34. The peptide analysis involving trypsin-digestion of immunocyte-derived S100 and authentic S100 protein did not resolve a definite peptide map, presumably due to low levels of detection. It is concluded that the cells of the immune system contain proteins that are antigenically related to S100, but differ in size and charge.

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