EFFECTS OF TUMOR-NECROSIS-FACTOR-ALPHA (TNF-ALPHA) ON THE PHOSPHOLIPID-METABOLISM OF TETRAHYMENA-PYRIFORMIS

The effect of (0.05 ng ml(-1) and 0.1 ng ml(-1)) TNF alpha on the phos pholipid metabolism of Tetrahymena pyriformis was studied. The amount of phosphatidyl choline (PC), phosphatidyl inositol (PI), phosphatidic acid (PA), phosphatidyl ethanolamine (PE), diacylglycerol (DAG), arac hidonic acid (AA) and ceramide was higher, but the phosphatidyl inosit ol 4 phosphate (PIP) and phosphatidyl inositol bis-phosphate (PIP2) as well, as sphingomyelin (SM) content was lower in TNF alpha-treated ce lls than in the controls. In the culture medium (secreted forms) this situation was reversed. There were differences in the results gained b y incorporation of [H-3]-palmitic acid or P-32 into the phospholipids. To control the functional effects of TNF alpha in Tetrahymena, the ra te of cell division, the condensation of chromatin, the viability of c ells and morphometrical values have been studied. The cytokine reduced cell growth, altered morphometric indices and increased chromatin con densation, however cell viability was not influenced. The results demo nstrate the effects of TNF alpha at a low level of evolution, what is realized by changes in the phospolipid metabolism participating in sig nalling pathways. (C) 1998 John Wiley & Sons, Ltd.