What is the three signal model of T cell mediated rejection?
• Signal 1: Antigen triggers T-cell receptors and synapse formation occurs.
• Signal 2: Signal 1 allows co-stimulation of antigen-presenting cells to occur.
• Signal 3: Signal 1 and signal 2 stimulate a cascade of intracellular events culminating in the initiation of the T-cell cycle; stimulation of the T-cell cycle allows T cells to infiltrate the graft.
• Summary effect is to inhibit T-cell receptor activation, cytokine production, and subsequent lymphocyte proliferation to prevent rejection.