Failure of Hypothalamic Lesions to Protect against Experimental Allergic Encephalomyelitis (EAE) in the rat

Summary

Thirty-two male Lewis rats were electrolytically lesioned in various hypothalamic and tegmental areas 1 day prior to the administration of an encephalitogenic antigen. Lesions of these areas have previously been shown to prevent anaphylactic shock. Ninty-two percent of the controls but only 50% of the rats with electrolytic lesions exhibited clinical signs of EAE 15 days after administration of antigen. Microscopic examination of nervous tissue, however, indicated that 31 of the 32 rats had inflammatory lesions of the central nervous system characteristic of EAE. Electrolytic lesions also did not prevent the changes in stress organ weights, body weights, and hematologic changes which occurred in control EAE rats. Hypothalamic lesions that would have blocked anaphylactic shock in the rat and guinea pig reduced the clinical signs of EAE but had no great effect on the histologic course of disease. Thus, delayed and humoral hypersensitivities, as represented by EAE and anaphylactic shock, may constitute different immunologic phenomena in the rat.