Table 2.
Summary of key studies of checkpoint inhibitory receptors on NK cells.
| Marker | Context | Species | References |
|---|---|---|---|
| Minimal PD-1 Increased TIGIT | Murine NK cells after CMV infection or acute leukemia; human NK cells incubated with cytokines or isolated from solid tumors | Human and Murine | [74] |
| Increased LAG-3 and PD-1 on adaptive but not conventional NK cells after seven days of stimulation | Checkpoint receptor expression compared on adaptive or conventional NK cells stimulated with activating antibodies for seven days | Human | [49] |
| Increased PD-1 on NK cells from spleen | Tissue specific NK cells examined in mice with Murine CMV infection | Murine | [35] |
| Increased TIGIT PD-1 < 10% expression | Intratumoral NK cells from mice with colon, breast, fibrosarcoma, and melanoma tumors | Murine | [81] |
| PD-1 expression on NK cells associated with more degranulation and IFN-γ secretion | Expression compared on tumor infiltrating NK cells | Murine | [82] |
| PD-1 expression increased after 12 days on expanded NK cells but not associated with functional deficits | Expression of PD-1 evaluated on NK cells after in vitro expansion with K562 expressing membrane bound IL-15 and 4-1BB ligand | Human | [83] |
| Increased PD-1 | Peripheral blood NK cells from patients with digestive cancers compared to healthy donors | Human | [84] |
| PD-1 expressed on 25% | Examination of peripheral blood NK cells from healthy donors seropositive for CMV | Human | [70] |
| Increased PD-1 | Comparison of NK cells from patients with Kaposi sarcoma compared to asymptomatic HHV-8 carriers | Human | [71] |
| Increased PD-1 on peripheral blood NK in patients with renal cell carcinoma | Compared PD-1 on NK cells from renal cancer patients before nephrectomy to healthy donors | Human | [68] |
| No increase in PD-1 TIM-3 expression associated with NK dysfunction | Compared NK cells from metastatic melanoma to healthy donors | Human | [85] |
| Increased PD-1 | NK cells compared in Post-Transplant Lymphoproliferative Disorder compared to transplant patients and healthy donors | Human | [72] |
| Increased PD-1 | NK cells from multiple myeloma patients compared to healthy donors | Human | [66] |