Escape from thymic deletion and anti-leukemic effects of T cells specific for hematopoietic cell-restricted antigen.

Ju, Ji-Min; Jung, Min Ho; Nam, Giri; Kim, Woojin; Oh, Sehwa; Kim, Hyun Duk; Kim, Joo Young; Chang, Jun et al. · Nat Commun · 2018

basic_science · Level V

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Abstract

Whether hematopoietic cell-restricted distribution of antigens affects the degree of thymic negative selection has not been investigated in detail. Here, we show that T cells specific for hematopoietic cell-restricted antigens (HRA) are not completely deleted in the thymus, using the mouse minor histocompatibility antigen H60, the expression of which is restricted to hematopoietic cells. As a result, low avidity T cells escape from thymic deletion. This incomplete thymic deletion occurs to the T cells developing de novo in the thymus of H60-positive recipients in H60-mismatched bone marrow transplantation (BMT). H60-specific thymic deletion escapee CD8<sup>+</sup> T cells exhibit effector differentiation potentials in the periphery and contribute to graft-versus-leukemia effects in the recipients of H60-mismatched BMT, regressing H60<sup>+</sup> hematological tumors. These results provide information essential for understanding thymic negative selection and developing a strategy to treat hematological tumors.

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