Dipeptidylpeptidase IV activity in Meissner corpuscles of rhesus monkey and its possible function.

Histochemical investigation by means of light and electron microscopy revealed the presence of dipeptidylpeptidase IV activity in Meissner corpuscles of macaque glabrous skin. The enzyme activity was found in fibroblast-like cells forming an incomplete capsule around the Meissner corpuscle. Distinct electron-dense reaction product due to dipeptidylpeptidase IV activity was consistently localized in the plasma membrane of specialized Schwann cells enveloping the unmyelinated portion of sensory axons. Their axolemma was devoid of dipeptidylpeptidase IV reaction product. The membrane-bound dipeptidylpeptidase IV activity presented here and the occurrence of substance P-containing nerve fibers in primate Meissner corpuscles referred to elsewhere, suggest the possible functional involvement of the enzyme in the production of substance P fragments, influenced in different ways by the axon proper and its surrounding Schwann cells.