Prostaglandin D2 and prostaglandin D synthetase in mast cell deficient mice

The content of prostaglandin D2 (PGD2) and the activity of PGD synthetase were measured in various tissues of mutant mice deficient in tissue mast cells (W/Wv) and congenic normal mice (+/+). The amounts of PGD2 were determined by the radioimmunoassay specific for PGD2. PGD2 was found in all tested tissues including brain, lung, stomach, spleen and skin of both genotypes in concentrations of a few to about thirty ng/g wet weight tissue, and in spite of the absence of tissue mast cells and the very low content of tissue histamine in W/Wv mice, there was no difference in tissue PGD2 amounts between W/Wv and +/+ mice. The activity of PGD synthetase was assayed in supernatant fraction (10,000 X g, 20 min) of tissue homogenates in the presence or absence of 1 mM GSH. All the tissues of both genotypes listed above showed considerable activity of PGD synthetase, and no difference in tissue PGD synthetase activity was found between W/Wv and +/+ mice. These results suggest that mast cells contribute little to the total amount of PGD2 and PGD synthetase activity in various tissues of mice, and that tissues can synthesize PGD2 independently of tissue mast cells.