Acute Serum Sickness Induced Immunologic Injury of the Choroid Plexus; With Particular Reference to the Effect of Prednisolone and the Nature of the Interstitial Cell

ABSTRACT

Immune complex deposits have been found in the choroid plexus in patients with systemic lupus erythematosus, and it can be assumed that an immune complex injury to the choroid plexus might be related to the neuropsychiatric disorder seen in patients with SLE. Acute serum sickness was experimentally induced in rabbits by intravenous injection of crystalized BSA. Prednisolone in conventionl dosage was administered to study the immunologic injury of the choroid plexus as well as the mechanisms involved in the prednisolone effect. Light, electron microscopic and immunofluorescent studies were made. The host immunoglobulins(IgG, IgA, IgM) and beta 1 C globulin were demonstrated in the choroid plexus. Histopathological findings included mild to moderate interstitial and perivascular lymphocyte and plasma cell infiltrations and edema. Control animals showed no immune deposits and no histopathologic changes. Electron microscopic findings comparing the immunofluorescent and histopathologic changes were minimal, and showed sparse, vague electron dense deposits particularly in the interstitial spaces, knob-like focal thickening of vascular basement membrane, swelling of endothelial cells, and some accentuation of interstitial cells. The morphologic and functional similarities of the choroid plexus and glomerular basement membrane, the findings in morphologic, electron microscopic and immunofluorescent examinations of the experimental rabbits, along with the observed effects of prednisolone, together with similar reports in the recent literature suggest that immunologic injury of the choroid plexus could be considered as a new disease entity. This immunologic injury might play a significant role in neuropsychiatric disorders in the long standing immune complex deposit diseases. The very interesting finding is the nature and function of the interstitial cell between the endothelial (vascular) and epithelial side basement membranes, and speculation as to whether or not the role of this interstitial cell in choroid plexus injury may be in its possible analogy with glomerular mesangial cells.