Neonatal induction of tolerance to T(h)2-mediated autoimmunity in rats

Brown-Norway (BN) rats are highly susceptible to drug-induced immune dysregulations and when injected with mercuric chloride (HgCl(2)) or sodium aurothiopropanolsulfonate (ATPS), they develop a syndrome characterized by a polyclonal B cell activation depending upon CD4(+) T(h)2 cells that recognize self-MHC class II molecules. Since peripheral tolerance of T(h)2 cells might be crucial in the prevention of immunological manifestations such as allergy, establishing conditions for inducing tolerance to HgCl(2)- or ATPS-mediated immune manifestations appeared to be of large interest. We report here that BN rats neonatally injected with HgCl(2): (i) do not develop the mercury disease, (ii) remain resistant to HgCl(2)-induced autoimmunity at 8 weeks of age and later, provided they are regularly exposed to HgCl(2), (iii) are still susceptible to ATPS-induced immune manifestations, and (iv) exhibit spleen cells that adoptively transfer tolerance to HgCl(2)-induced autoimmunity in naive, slightly irradiated, syngeneic recipients. These findings demonstrate that dominant specific tolerance can be neonatally induced using a chemical otherwise responsible for T(h)2-mediated autoimmunity.