Blood-CNS Barrier in Experimental Poliomyelitis.

Abstract

A selective mechanism regulating the exchange of substances between the blood and the central nervous system, and usually referred to as the hemato-encephalic or blood-brain barrier, has long been known to exist. McIntosh and Fildes showed that after intravenous injection of salvarsan no arsenic could be found in the brain, although it could be detected in tissues outside the central nervous system. Friedemann and Elkeles, among others, believe that the mechanism controlling the passage of substances between the blood and the brain is localized in the cerebral capillaries and is intimately concerned with the permeability of the vessel walls. Trotter has emphasized the virtually complete isolation of nervous tissue from the somatic tissues, a point of considerable importance in the pathogenesis of neurotropic virus diseases and one frequently overlooked in procedures devised to confer immunity against these viruses. Thus, W. S. Gordon, using louping-ill virus, found the central nervous tissue of sheep difficult to immunize. F. B. Gordon, of this laboratory, attempting to immunize Rhesus monkeys to poliomyelitis virus, experienced the same difficulty. The striking ineffectiveness of the vascular route of inoculation in producing poliomyelitis in Rhesus monkeys (Macaca mulatta), unless comparatively huge amounts of virus are used, presumably rests on the ability of an intact blood-CNS barrier to keep injurious substances of hematogenous origin from reaching the nervous tissues. Using the technic devised by Sawyer and Lloyd for a yellow fever protection test, we attempted to damage the barrier by intracerebral injection of sterile starch. Nine normal and 2 immune monkeys were given intravenously a single injection of 10 cc. of a rapidly centrifuged, 10% crude virus-cord suspension. Three of the normal animals and both immune animals were injected intracerebrally with one cc. of a sterile 2% starch solution.