Revisiting Tolerance Induced by Autoantigen in Incomplete Freund’s Adjuvant

Abstract

Injection of autoantigens in IFA has been one of the most effective ways of preventing experimental, T cell-mediated, autoimmune disease in mice. The mechanism that underlies this protection has, however, remained controversial, with clonal deletion, induction of suppressor cells or of type 2 immunity being implicated at one time or another. Using high resolution enzyme-linked immunospot (ELISPOT) analysis, we have revisited this paradigm. As models of autoimmunity against sequestered and readily accessible autoantigens, we studied experimental allergic encephalomyelitis, induced by myelin oligodendrocyte glycoprotein, proteolipid protein, myelin basic protein, and renal tubular Ag-induced interstitial nephritis. We showed that the injection of each of these Ags in IFA was immunogenic and CD4 memory cells producing IL-2, IL-4, and IL-5, but essentially no IFN-γ. IgG1, but not IgG2a, autoantibodies were produced. The engaged T cells were not classic Th2 cells in that IL-4 and IL-5 were produced by different cells. The IFA-induced violation of self tolerance, including the deposition of specific autoantibodies in the respective target organs, occurred in the absence of detectable pathology. Exhaustion of the pool of naive precursor cells was shown to be one mechanism of the IFA-induced tolerance. In addition, while the IFA-primed T cells acted as suppressor cells, in that they adoptively transferred disease protection, they did not interfere with the emergence of a type 1 T cell response in the adoptive host. Both active and passive tolerance mechanisms, therefore, contribute to autoantigen:IFA-induced protection from autoimmune disease.

Dissociation of Experimental Allergic Encephalomyelitis Protective Effect and Allergic Side Reactions in Tolerization with Neuroantigen

“…IL-5 producers, which are prevalent after a single i.p. Ag:IFA injection (21,22) and which also become prominent after repeated s.c. injections (Fig. 2), were present in low but clearly detectable frequencies, at 27 per million spleen cells in primarily injected mice.…”

“…Ag injections with IFA are not a conceivable treatment for humans; however, s.c. injections with mineral oil (or with related lipids) are approved for clinical studies. Our previous studies have suggested that the protective effect of autoantigen:IFA injections in autoimmune models is Ag specific and T cell mediated: this treatment also protects B cell knock out mice, and the protection can be adoptively transferred with T cells (22). Unlike the immune-modulating effects of i.p.…”

“…Unlike the immune-modulating effects of i.p. IFA injections that have been closely studied in mice (19,21,22,42), the effects of s.c. IFA injections-and in particular of repeat injections-are not well characterized. Our first set of data aimed at filling this gap of knowledge.…”

“…22). The protection is specific: for example, injection of PLP:IFA prevents EAE, whereas renal tubular Ag:IFA does not.…”

“…Similarly, the latter treatment, but not the former, abrogates the development of the autoimmune antitubular basement membrane disease in the kidney. This protection can be adoptively transferred with CD4 cells that display an Ag-specific type 2 cytokine signature (22). Type 2 T cells seem to be viable candidates for mediating this type of "infectious tolerance."…”