Lipid Analyses of Isolated Plasma Membranes of Lymphoid Cells in Benign Thymomas of Bufffalo/Mna Rats

Abstract

Plasma membranes were isolated from lymphoid cells of benign thymomas obtained from inbred BUF/Mna rats (21 mo old) and from normal thymocytes obtained from young rats (7 wk old) of the same strain. The isolated plasma membranes were electron microscopically pure, and the specific activities of Na⁺, K⁺-ATPase, and 5′-nucleotidase were enhanced. The lipid compositions of the plasma membranes from these two sources were analyzed and compared. The cholesterol and plasmalogen contents of membranes from both sources were similar, but the phospholipid content of the benign thymoma lymphoid cell membranes was slightly lower than that of the normal thymocytes, resulting in a somewhat higher molar ratio of cholesterol to phospholipid. The plasma membranes of the thymoma lymphoid cells also exhibited a slightly higher micro-viscosity as measured with fluorescence polarization. No significant differences were observed in the phospholipid compositions of the two membrane preparations.