Mediators include leukotrienes, histamines, prostaglandin, and tryptase. Antihistamines are not effective, because the symptoms are not mediated by histamines. The antibodies will cause cells in the body to produce histamines. About 30% of people are sensitive to biogenic amines, such as histamines. Larval "hairs" may be stinging in some species, due to histamines their caterpillar makes. Their venom contains haemolytic and eicosanoid elements and histamines. Direct expansion causes tissue damage, with the release of histamines and their associated affects. Histamines are proteins associated with many allergic reactions.