Leukotriene production by macrophage cells irradiated with cobalt-60 gamma irradiation

Leukotriene biosynthesis was assessed in vitro following treatment of rat peritoneal macrophage cells with Ca-ionophore A23187 or Co-60 gamma irradiation. Pre-incubated macrophage cells cultured in plastic flasks under 5% CO$\backslash sb2$ and 95% moisturized air at 37 $\backslash sp\circ$C were labeled with ($\backslash sp14$C) arachidonic acid for 12 hours prior to administration of Ca-ionophore or various doses of gamma radiation(2 Gy - 32 Gy). Treatment was stopped after one hour incubation with addition of isopropanol to the culture medium. The arachidonic acid metabolites were extracted with diethyl ether, and analyzed by high performance liquid chromatography using a C$\backslash sb18$ reverse phase column. The eluted materials were detected using an in line radioactivity flow detector equipped with a dot matrix printer. The results indicated that both treatments caused quantitatively higher conversion of arachidonic acid to leukotriene C$\backslash sb4$ and release of several other radiolabeled metabolites when compared to the control. However, in all treatments including the control the amount of unmetabolized arachidonic acid released from cells in the culture medium was significantly higher than the released metabolites. The release of arachidonic acid from the cell membrane was quantitatively related to the presence of fetal bovine serum (FBS) in the culture medium during the treatment period. In the absence of FBS the stimulated macrophage cells produced a larger amount of arachidonate metabolites with a significant decrease in the release of free arachidonic acid compared to those that had FBS during the treatment period. In the presence of ibuprofen but no FBS, Ca-ionophore stimulated macrophage cells produced both qualitatively and quantitatively higher amounts of arachidonates including LTC$\backslash sb4$ compared to other treatments.