Quantitation of arachidonic acid lipoxygenase products in malignant and nonmalignant effusions

The arachidonic acid lipoxygenase products 15-hydroxyeicosatetraenoic acid, 12-hydroxyeicosatetraenoic acid, and 5-hydroxyeicosatetraenoic acid and the arachidonic acid cyclooxygenase product prostaglandin E2 were quantitated in 11 malignant and 10 nonmalignant peritoneal and pleural effusions. The mean quantities of 15-hydroxyeicosatetraenoic acid in malignant and nonmalignant effusions were 10 and 46 ng/ml, respectively (p less than 0.05), and the mean quantities of 5-hydroxyeicosatetraenoic acid in malignant and nonmalignant effusions were less than 1 ng/ml and 12 ng/ml, respectively (p less than 0.05). The quantities of 12-hydroxyeicosatetraenoic acid and prostaglandin E2 were also reduced in malignant effusions but the reduction was not statistically significant. Both the protein content and the total number of leukocytes correlated with the quantity of prostaglandin E2 in the effusions, whereas no consistent correlation was found with the quantity of lipoxygenase products in the effusions. Lipoxygenase products are critical mediators of neutrophil, lymphocyte, and macrophage function. Thus, the reduced capacity to lipoxygenate arachidonic acid associated with malignant conditions may contribute to the impaired immune responsiveness of patients with cancers.