Complex sentence: T-cells which have receptors with sufficient affinity for self-MHC molecules are selected.many self protein antigens are processed and presented by thymic antigen presenting cells (APCs) in association with self MHC.
Split into simpler sentences: T-cells which have receptors with sufficient affinity for self-MHC molecules are selected. Many self protein antigens are processed and presented by thymic antigen presenting cells (APCs) in association with self MHC.