ENKEPHALIN-LIKE IMMUNOREACTIVITY IN HUMAN SKIN IS FOUND SELECTIVELY IN A FRACTION OF CD68 - POSITIVE DERMAL CELLS - INCREASE IN ENKEPHALIN-POSITIVE CELLS IN LESIONAL PSORIASIS

Opioid peptides are synthesized in neurons, endocrine cells, monocytes /macrophages and B and T lymphocytes, They interact with opioid recept ors located on immune cells and nociceptive nerve terminals, Because o pioid peptides might be of importance in inflammatory skin diseases, f or example psoriasis, sections of skin from psoriatic patients were im munohistochemically stained with antisera against methionine and leuci ne enkephalin, CD68 (KP1, PG-M1), calprotectin (M747), M130 (Ber-MAC3) , CD1a and CD3. Enkephalin-like activity was detected selectively in d ermal CD68-positive macrophages/monocytes. The activity showed no asso ciation with the activation markers M747 and Ber-MAC3, There was a sta tistically significant increase in enkephalin-positive cells in involv ed psoriatic skin compared with uninvolved and normal skin, These resu lts were confirmed by radioimmunoassay which showed elevated levels in extracts from involved psoriatic skin compared with uninvolved skin ( 81%) and normal skin (204%), Furthermore, preproenkephalin mRNA of an expected size was detected in involved psoriatic skin, If the increase d levels of enkephalins present in monocytes/macrophages in psoriatic skin lesions reach the threshold for biological activity, they may pla y a role in the regulation of the inflammatory processes seen in this skin disease.