EXPRESSION OF ENDOPEPTIDASE-24.11 (COMMON ACUTE LYMPHOBLASTIC-LEUKEMIA ANTIGEN CD10) IN THE SCIATIC-NERVE OF THE ADULT-RAT AFTER LESION ANDDURING REGENERATION

Endopeptidase-24.11, which is identical with the common acute lymphobl astic leukaemia antigen CD10 (CALLA), is a cell surface Zn2+ metallopr otease that regulates peptide-induced responses in different tissues, including the nervous and immune systems. In the peripheral nervous sy stem, high levels of the enzyme are present in all neonatal and early postnatal Schwann cells, while as myelination proceeds it is gradually suppressed in the majority of cells that form myelin but retained in non-myelin-forming cells in the adult animal. In the present study we have investigated the effects of transection, crush and regeneration o f the adult rat sciatic nerve on the expression of the endopeptidase b y Schwann cells in situ. Endopeptidase-24.11 was monitored by immunocy tochemistry using the monoclonal anti-endopeptidase antibody 23B11. Fo r comparison, a parallel study was carried out with a monoclonal antib ody directed against the rat nerve growth factor receptor. We found th at (i) all Schwann cells of the distal segment re-expressed endopeptid ase-24.11 as early as 4 days after axotomy, the level of immunostainin g reaching a maximum after 2 weeks, (ii) axonal regeneration repressed Schwann cell expression of endopeptidase-24.11, and (iii) the inducti on of the nerve growth factor receptor followed a similar pattern to t hat of endopeptidase-24.11 in the transected and crushed nerve. Enzyma tic amplification of endopeptidase-24.11 cDNA from normal and axotomiz ed adult rat sciatic nerve confirmed the expression of endopeptidase-2 4.11 in these tissues. Our results show that the expression of endopep tidase-24.11 in Schwann cells, as is the case with the nerve growth fa ctor receptor, is induced by the loss of the normal axon-Schwann cell contact. The significant increase in the expression of endopeptidase-2 4.11 by Schwann cells after axonal damage suggests that the enzyme cou ld play a role in axonal regeneration.