ARACHIDONIC-ACID IS A PREFERRED ACETYL DONOR AMONG FATTY-ACIDS IN THEACETYLATION OF P-AMINOBENZOIC ACID BY HUMAN LYMPHOID-CELLS

We have previously reported that human lymphoid cells, such as periphe ral blood mononuclear leukocytes (PBML) and the T-cell leukemia line J urcat, synthesize p-acetamidobenzoic acid from p-aminobenzoic acid (PA BA) and a two carbon fragment from arachidonic acid (AA), conceivably derived from beta-oxidation. Here we demonstrate that AA is a preferre d substrate in this acetylation reaction over other common fatty acids such as palmitic (PA), oleic, linoleic or linolenic. This was unexpec ted because AA is not considered as a fuel fatty acid. In Jurcat cells , AA is also preferred as a substrate for beta-oxidation over PA. In c ontrast, in PBML, PA was clearly preferred as substrate for beta-oxida tion over AA, in accordance with previous observations. The difference between Jurcat cells and PBML was not dependent on culture conditions , because phytohemagglutinin and interleukin-2 activated PBML, kept in culture, showed the same PA preference as freshly prepared non-activa ted PBML. Furthermore, we observed differences between Jurcat cells an d PBML in their relative content of fatty acids and in the incorporati on of PA and AA into triacylglycerols and phospholipids. Taken togethe r, our results show differences in beta-oxidation between Jurcat cells and PBML, and suggest the involvement of peroxisomal, besides mitocho ndrial, beta-oxidation, in the acetylation of PAPA with fatty acids as acetyl donors.