IDENTIFICATION OF PHOSPHATIDATE NONLAMELLAR PHASES ON LIPOSOMES BY FLOW-CYTOMETRY

This study is the first report that demonstrates nonlamellar arrangeme nts, or lipidic particles, of phosphatidate inserted in the lipid bila yer of liposomes using polyclonal antibodies from mice and flow cytome try. Sera immunoreactivity was analyzed using liposomes that displayed smooth bilayers or phosphatidate particles, as shown by electron micr oscopy. This cytofluorimetric analysis showed that immune mice sera ha ve a specific immunoreactivity with the phosphatidate particles formed by Mn2+, which also cross-reacted with those formed by Ca2+ and with the cardiolipin particles formed by Mn2+. In addition, these immune se ra hardly reacted with smooth bilayered Liposomes, independently of th e lipid composition studied. Thus, this new methodology can be applied to demonstrate nonlamellar molecular arrangements of lipids in biolog ical membranes.