The cytotoxicity of a cobra venom phospholipase to mouse lymphoma cells

A series of phospholipases were compared as to their ability to disrupt variants of S-49 mouse lymphoma cells. The basic, type-A₂-phospholipase (named P₃-Menashe et al. 1980) derived from the venom of the cobra snake Naja mossambica mossambica has demonstrated unique cytolytic properties in the following aspects: (1) While being devoid of any direct hemolytic activity and demonstrating very low cytotoxicity to normal mouse lymphocytes, P₃ has induced a potent lytic action on S-49 cells and several mutants derived from them. (2) When P₃ was compared to a cytolytic cardiotoxin derived from the same venom it was found to possess higher cytotoxicity. (3) The ability of P₃ to disrupt S-49 cells could not be reproduced by lysophosphatidylcholine - a common and strongly hemolytic product of phospholipase A₂ enzymatic action. (4) The possible relation between the high susceptibility of lymphoma cells to the lytic action of P₃ and their unique composition and/or arrangement of membranal phospholipids is discussed.