EXPRESSION OF THE LOW-AFFINITY NGF RECEPTOR DURING HUMAN MUSCLE DEVELOPMENT, REGENERATION, AND IN TISSUE-CULTURE

The expression of the low-affinity NGF receptor (LNGFR) during human m uscle development, regeneration, and in tissue culture was analyzed us ing a murine monoclonal antibody to human LNGFR (MAb ME 20.4). Muscle cells from 12-22-week fetuses stained strongly for LNGFR. In adult nor mal muscle, only intramuscular nerve endings showed immunoreactivity w ith MAb ME 20.4, but no staining was detected in muscle fibers. In Duc henne muscular dystrophy, immunohistologically demonstrable LNGFR was present in regenerating muscle fibers. In these fibers, LNGFR gene exp ression was also demonstrated at the transcriptional level using in si tu hybridization with riboprobes coding with human LNGFR. Cultures fro m human fetal and adult muscle were studied by double label indirect i mmunofluorescence microscopy with MAb ME 20.4 and antisera against hum an fetal myosin. Most myosin-positive cells, both at the myoblast and myotube stages, displayed surface LNGFR immunostaining. In cells from fetal muscle, LNGFR was detected during the first 2 weeks in vitro, wh ereas in cells from adult muscle the expression of LNGFR was observed for up to 7 weeks. These findings suggest a potential involvement of L NGFR in human muscle development and regeneration. (C) 1994 John Wiley and Sons, Inc.