Antigen transfer in the thymus is the transmission of self-antigens between thymic antigen-presenting cells which contributes to the establishment of T cell central tolerance.
Thymus represents an origin of T cell development and its responsibility is to select functional but also safe T cells which will not attack self tissues. Self-harmful T cells, further referred to as autoreactive T cells, originate in the thymus because of the stochastic process called V(D)J recombination which conducts the generation of T cell receptors (TCRs) and enables their limitless variability. Two processes of central tolerance take place in thymic medulla, namely clonal deletion (recessive tolerance) and T Regulatory cells selection (dominant tolerance) which force autoreactive T cells to apoptosis or skew them into suppressor T regulatory cells (TRegs), respectively, in order to protect body against manifestations of autoimmunity.
These processes are mediated especially by unique subset of stromal cells called Medullary thymic epithelial cells (mTECs) via presentation of Tissue restricted antigens (TRAs) that represent self tissues from almost all parts of the body.