Inhibition of in vitro peripheral myelin formation by monoclonal anti- galactocerebroside

Abstract

This work investigates the role of galactocerebroside (GalC) in peripheral myelin formation. A monoclonal antibody against GalC was introduced into a myelinating culture system consisting of rat sensory neurons and Schwann cells, without other cell types. At levels that saturated Schwann cell surface GalC, anti-GalC IgG prevented by more than 99% the appearance of myelin sheaths. Ensheathment and basal lamina deposition were unaffected and many Schwann cells were in the 1:1 relationship that typically develops between Schwann cells and axons prior to myelination. Thus, the anti-GalC antibody did not interfere with the formation of the mesaxon but prevented its elongation. When experimentally restrained from myelination, Schwann cells did not accumulate the myelin proteins PO and basic protein; only low levels were expressed. The proposed mechanism of inhibition is the removal of GalC from Schwann cell surfaces by internalization of the GalC-anti-GalC antigen-antibody complex. This apparently prevented the interaction of adjacent cell surfaces during the elongation of Schwann cell membranes that constitute the myelin lamellae.