Abstract
BACKGROUND: Activation of mast cells and the systemic release of histamine are common side effects of opiates such as codeine and morphine. In some individuals, codeine not only elicits a sizable early response due to mast cell degranulation, but can also lead to late cutaneous allergic inflammation possibly through the production of chemokines. However, individuals who exhibit a late phase reaction to codeine often do not react to its synthetic analog, meperidine. The goal of this study was to test whether codeine and meperidine induce secretion of inflammatory mediators in human mast cells. METHODS: To characterize opiate activation of human mast cells, we stimulated cultured human (LAD2 cell line and CD34+-derived) mast cells with codeine and meperidine and measured degranulation and chemokine production. RESULTS: Codeine, but not meperidine, activated human mast cell degranulation within 30 min in a dose-dependent manner. Degranulation was blocked by the phosphoinositol-3 kinase (PI3K) inhibitor, wortmannin, and pertussis toxin but not by Ro-31-8220, a PKC inhibitor or forskolin, a cyclic adenylyl cyclase activator. After 3 and 8 h of stimulation, codeine, but not meperidine, activated human mast cells to release monocyte chemoattractant protein-1 (CCL2), regulated on activation, normal T expressed and secreted (RANTES, CCL5) and interleukin-8 (CXCL 8) but not inducible protein-10 (CXCL10). CONCLUSIONS: Codeine activates human mast cell degranulation and chemokine production by activating protein kinase A and PI3 kinase, possibly leading to NF-kappaB activation. Therefore, opiates may regulate late phase allergic inflammation by activating chemokine production by human mast cells.