The expression of LTA hydrolase and 5-lipoxygenase genes was studied in Raji cells, a Burkitt lymphoma derived B-cell line. Northern and Western blot analyses clearly showed the expression, both at the transcriptional and translational level, of the LTA4 hydrolase gene in these cells. However, expression of the 5-lipoxygenase gene was undetectable. Thus, the genes coding for the two enzymes required for biosynthesis of leukotriene B4 from arachidonic acid, 5-lipoxygenase and LTA4 hydrolase, were differentially expressed in the Raji cells.