Regulation of cytokine gene expression in experimental autoimmune encephalomyelitis.
We previously reported that recovery of Lewis rats from experimental autoimmune encephalomyelitis (EAE) is associated with the appearance of suppressor T cells (Ts). These Ts secrete TGF-beta which down-regulates the production of inflammatory cytokines by the effector T cells that mediate this disease. In the present study, we immunized Lewis rats with myelin basic protein (MBP)+CFA, and evaluated purified T cells and MBP-activated spleen cells (SpC) during the paralytic phase (day 12) and after recovery (days 30-33) for TGF-beta and interferon (IFN)-gamma mRNA. We used reverse transcriptase-polymerase chain reaction (RT-PCR), quantitated on the basis of beta-actin mRNA. Abundant IFN-gamma mRNA was present in MBP-activated SpC obtained on day 12. In contrast, only trace IFN-gamma mRNA was detected in day 30 activated SpC, and no IFN-gamma mRNA was present in purified, nonactivated T cells obtained at either time. The level of IFN-gamma mRNA correlated with secretion of IFN-gamma as determined by ELISA on SpC culture supernatants, and with severity of adoptively transferred EAE by the activated SpC. Thus, it appears that IFN-gamma mRNA is both transcribed and translated in response to antigen activation, resulting in secretion of IFN-gamma by the disease-inducing Te. In contrast, when we used RT-PCR to investigate the expression of TGF-beta mRNA, we found the transcript present in isolated T cells and MBP-activated SpC obtained from rats at both days 12 and 30. The presence of TGF-beta mRNA at time points corresponding to both clinical EAE and recovery suggests post-transcriptional regulation of the production of this immunoregulatory cytokine.
Zitron
I M
IM
William Beaumont Hospital Research Institute, Royal Oak, Michigan 48073, USA.
Reddy
B P
BP
Gould
K E
KE
Stepaniak
J A
JA
Swanborg
R H
RH
D000208:Acute Disease; D000818:Animals; D002478:Cells, Cultured; D003289:Convalescence; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D008213:Lymphocyte Activation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011917:Rats, Inbred Lew; D013154:Spleen / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000235:genetics
D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D007371:Interferon-gamma