Possible role of zonula occludens of the myelin sheath in demyelinating conditions

AUTOIMMUNE mechanisms may play a major role in several human demyelinating diseases¹. Myelin contains components, principally a basic class of protein, which, when injected systemically with an adjuvant, elicit in the experimental animal a demyelinating encephalomyelitis or neuritis with perivascular infiltration of lymphocytes and inflammatory cells^1,2. A satisfactory hypothesis is that the potential self-antigens are secluded from the immune systems in the normal living animal³. Evidence for such a specific compartmentation of myelin components, however, has been lacking up to now. This has led several authors to suggest alternative explanations ^1,4,5. Here we demonstrate the structural basis for a seclusion mechanism within both peripheral and central myelin sheaths in different animal species.