Changes in arachidonic acid content of X-irradiated human lymphocytes and plasma membrane fractions

The 14C-arachidonic acid content of pre-labelled human lymphocytes was followed during in vitro incubation in untreated and X-irradiated cells. Loss of about 35-40 per cent of the incorporated radioactivity was found already at 10 minutes after irradiation as detected in whole cells, phospholipid, free fatty acid and phosphatidylcholine fractions of plasma membranes. When pulse labeling with 14C-arachidonic acid was performed at various intervals after in vitro irradiation, the uptake of precursor by irradiated cells did not differ from untreated ones. At the same time the activity of phospholipid, free fatty acid and phosphatidylcholine fractions was approximately 50 per cent lower compared to the control, then it increased gradually reaching the control level.