Indeed, and as shown in Figure 4, the aggravation of anaphylaxis by ASA was reversed by prior application of a 15-hydroxyprostaglandin dehydrogenase (PGDH) inhibitor (PGDH-I), which interferes with PGE2 degradation, thereby confirming that a lower PGE2 level was the aggravating factor (Figure 4A). This evidence concerns the gene HPGD and anaphylaxis.