The Storage Lipids in Tangier Disease: A PHYSICAL CHEMICAL STUDY

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Abstract

The physical states and phase behavior of the lipids of the spleen, liver, and splenic artery from a 38-yr-old man with Tangier disease were studied. Many intracellular lipid droplets in the smectic liquid crystalline state were identified by polarizing microscopy in macrophages in both the spleen and liver, but not in the splenic artery. The droplets within individual cells melted sharply over a narrow temperature range, indicating a uniform lipid composition of the droplets of each cell. However different cells melted over a wide range, 20-53°C indicating heterogeneity of lipid droplet composition between cells. Furthermore, most of the cells (81%) had droplets in the liquid crystalline state at 37°C. X-ray diffraction studies of splenic tissue at 37°C revealed a diffraction pattern typical of cholesterol esters in the smectic liquid crystalline state. Differential scanning calorimetry of spleen showed a broad reversible transition from 29-52°C, with a maximum mean transition temperature at 42°C, correlating closely with the polarizing microscopy observations. The enthalpy of the transition, 0.86±0.07 cal/g of cholesterol ester, was quantitatively similar to that of the liquid crystalline to liquid transition of pure cholesterol esters indicating that nearly all of the cholesterol esters in the tissue were free to undergo the smectic-isotropic phase transition.

Authors

Saul S. Katz, Donald M. Small, Jacob G. Brook, Robert S. Lees