Characterization of the T lymphocyte subsets and lymphoid populations involved in the induction of low-dose oral tolerance to human thyroglobulin

Using mice deficient in CD8 alpha, TCR delta, CD4, or CD120a, as well as ad optive transfer experiments in wild-type and RAG-1-deficient mice, we chara cterized the T lymphocyte subsets and lymphoid populations involved in the induction of low-dose oral tolerance to human thyroglobulin (hTg). The oral administration of hTg, but not the intraperitoneal (ip) administration of hTg, generates lymphocytes that can transfer tolerance. Purified CD8 alpha (+) lymphocytes successfully transfer tolerance, while the depletion of CD8 alpha or TCR delta lymphocytes prevents the transfer of tolerance. Oral to lerance can be induced in CD4-deficient mice and RAG-1-deficient mice recon stituted with cells from CD120a-deficient mice, but not in CD8 alpha-, TCR delta, or CD120a-deficient mice. These findings indicate that CD8a and TCR delta T lymphocytes are necessary for the oral induction and transfer of to lerance to hTg. Additionally, functional Peyer's patches are necessary for the induction of low-dose oral tolerance to hTg. (C) 2001 Academic Press.