Intramuscular interstitial cells of Cajal associated with mast cells survive nitrergic nerves in achalasia

Achalasia is dominated by injury to inhibi- tory nerves. As intramuscular interstitial cells of Cajal (ICC-IM) are proposed to form functional units with nitrergic nerves, their fate in achalasia may be critic- ally important. We studied the relationship between loss of nitrergic nerves and injury to ICC-IM in patients with achalasia and determined associations between ICC-IM and mast cells (MC), using quantitative immunohistochemistry and electron microscopy. Loss of neuronal nitric oxide synthase (nNOS) immu- noreactivity was completed within 3 years of acquiring achalasia. Thereafter, progressive ultrastructural in- jury to remaining nerve structures was evident. Within the first 2 years, the number of ICC-IM did not decline although ultrastructural injury was already present. Thereafter, loss of ICC-IM occurred unrelated to dur- ation of disease. Damage to ICC-IM appeared unre- lated to nerve injury. A significant MC infiltration was observed in the musculature; the number of MC was positively related to the persistent number of ICC-IM. Mast cell formed close contacts with ICC-IM and piecemeal-degranulation occurred towards ICC-IM. In conclusion, injury to ICC-IM in achalasia is variable, but not related to duration of disease and injury to nitrergic nerves. MC are prominent and form close functional contact with ICC-IM which may be responsible for their relatively long survival.