It was found in our study that high expression of PD-L1 was associated with the increase of CD8+ T cells, based on which we speculate that PD-L1 expression is induced by CD8+ T cell infiltration, and upregulation of PD-L1 expression is due to the feedback of inhibition of the anti-tumor immune activity in GISTs. The gene discussed is CD8A; the disease is neoplasm.