Studies have shown that the expression of TGF-β and NKG2DL (MICA/B, ULBP1–3) on the exosome surface in the extrapleural fluid of malignant mesothelioma downregulates the expression of NKG2D on immune cells, which is also an important factor causing tumor immune escape [68]. This evidence concerns the gene KLRK1 and neoplasm.