Balance of Th1/Th2 cytokines associated with the preventive effect of incomplete Freund's adjuvant on the development of adjuvant arthritis in LEW rats.

Complete Freund's adjuvant (CFA) could induce adjuvant arthritis (AA) in LEW rats and incomplete Freund's adjuvant (IFA) could induce oil induced arthritis (OIA) in DA but not in LEW rats. Lymph node cells (LNCs) from these AA and OIA rats showed increased mRNA expression of IFN-gamma, IL-2 and TNF-alpha but not IL-4. LNCs from IFA immunized LEW rats showed increased expression of IL-4, reduced expression of IFN-gamma and TNF-alpha and no IL-2, in contrast to IFA immunized DA rats. The pretreatment of IFA before CFA challenge could completely prevent AA in LEW rats and their LNCs showed increased expression of IL-4 and IFN-gamma but not IL-2 and TNF-alpha. In F1 (LEW x DA) rats, IFA could not induce OIA but the pretreatment of IFA before CFA challenge could induce very mild AA with 80% incidence, LNCs showing an elevated expression of all the above cytokines. These findings suggest that increased Th1 cytokine expression is associated with disease development and that increased IL-4 expression or the balance of Th2 over Th1 cytokine expression plays an important regulatory role in disease development. Copyright 2001 Academic Press.