Table 1.
Specificities of lung NK cells in non-neoplastic respiratory diseases.
| Diseases | Quantitative observations | Qualitative considerations | References | |
|---|---|---|---|---|
| Systemic Auto-immune Diseases | Sjögren Syndrome | Normal absolute count of Activated (HLA-DR+) NK cells in BALF | nd | (30) |
| Systemic Sclerosis | Normal absolute count of Activated (HLA-DR+) NK cells in BALF | nd | (30) | |
| Anti-synthetase Syndrome | NK cells infiltration of all areas of lung fibrosis | NK cell expression of Granzyme B, Significant CD69 expression | (31, 32) | |
| Inflammatory Diseases and/or Fibrosing diseases | Behçet Disease | Lower proportion of NK cells in BALF | Lower cytotoxicity | (33) |
| Sarcoidosis | Increased number of CD56bright NK cells in BALF | Immature phenotype with NKG2Ahigh & KIRlow predominant phenotype. Higher capacity to produce IFN-γ and TNF-α cytokines | (34–36) | |
| COPD | Normal count of CD56+CD16+ lung NK cells | Decreased CD8 expression associated with poor outcome, Higher cytotoxicity. Normal expression of the activating receptor NKG2D but abnormal expression of its ligands MICA/B by lung epithelial cells. | (37) | |
| Idiopathic Pulmonary Fibrosis | Presence of NK cells in BALF | Predisposing factor involving NKG2D-MICA/B pathway | (38) | |
| Allergy | Asthma Hypersensitivity Pneumonitis | Decreased proportion of CD56dim NK cells in BALF Higher number of NK cells in BALF | Increased expression of Granzyme A nd | (39) (29) |
| Infectious Diseases* | Influenza A Virus** | nd | Resident NK cells are hyperfunctional after ex vivo Infection, including degranulation, granzyme B expression and IFN-gamma expression | (11) |
| HCMV° | Higher proportion of lung NKG2C+ NK cells (BALF) of patients with HCMV viremia following lung transplantation | NKG2C+ NK cells are more mature and have higher proliferation capacities. All abnormalities are associated with poor outcomes. | (28) | |
HLA, Human Leukocyte Antigen; BALF, Broncho-alveolar lavage fluid; nd, not determined; HCMV, Human Cyto-megalo-virus; COPD, chronic obstructive pulmonary disease;
*
focuses on human studies although animal models exists for various infections (including Mycobacterium Tuberculosis, Klebsiella Pneumoniae…).
**
first infectious disease in which analyses have been performed according to the definition of resident lung NK cells,
°
studies are available only in the context of lung transplantation.