COMPETITIVE PCR QUANTIFICATION OF PROINFLAMMATORY AND ANTIINFLAMMATORY CYTOKINE MESSENGER-RNA IN THE CENTRAL-NERVOUS-SYSTEM DURING AUTOIMMUNE ENCEPHALOMYELITIS

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory dis ease of the central nervous system that can be induced by immunization with myelin basic protein (MBP)/complete Freund's adjuvant and serves as a model for multiple sclerosis. Recent studies have suggested that cytokines play a crucial role in the clinical course of EAE. To clari fy the roles of cytokines in EAE, we examined levels of interferon-gam ma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 1 (TGF-beta 1) and interleukin-10 (IL-10) mRNA in i solates from infiltrating inflammatory cells in EAE lesions induced in Lewis rats. The non-radioactive and sensitive competitive PCR method was employed to quantify the relative amounts of cytokine mRNA. Levels of both IFN-gamma and TNF-alpha mRNA were increased at the early stag e of EAE and rapidly decreased at the peak stage. On the other hand, T GF-beta 1 mRNA was demonstrated throughout the course of EAE as well a s under normal conditions and its amount paralleled the severity of EA E. IL-10 mRNA was detected by reverse transcription polymerase chain r eaction (RT-PCR) under normal conditions, but was below the level of d etection of competitive PCR. IL-10 mRNA expression peaked at the early stage of EAE and declined gradually thereafter. Taken together, these results suggest that IFN-gamma and TNF-alpha might play a crucial rol e in the development of EAE. Furthermore, it appears that the peak exp ression of IL-10 mRNA at the early stage and the following marked TGF- beta 1 expression at the peak stage might represent an important endog enous mechanism to limit the extent of inflammation and to prevent rel apse in the course of acute monophasic EAE.