NK<unk> s normally occupy the GI tract where they contribute to innate immunity by becoming active in killing pathogen-infected and cancerous<unk> s. The proliferating lymphocytes in NKCE and LG express CD56 and CD7 proteins on their<unk>  surface membrane, CD3γ protein in their cytoplasm, and granzyme B, perforin, and T-cell intracellular antigen-1 cytotoxic proteins within their cytoplasmic granules. This pattern of protein expression identifies these<unk> s as NK<unk> s that, because of their expression of the cytotoxic granule-bound proteins, have been activated. However, the cause(s) for the activation of these<unk> s as wells as for their rapid proliferation to produce NKCE and LG is unknown. To date, no evidence of NK<unk>  clonality (i.e.<unk> s developing from a single precursor) or for these<unk> s to bear gene mutations or chromosome abnormalities have been reported in NKCE or LG. These findings help distinguish LB and NKCE from many lymphomas and support the conclusion that neither disease is malignant. The NK<unk> s in LG and NKCE are not infected with the Epstein-Barr virus (EBV), as evidenced by their failure to express this virus's latency proteins and latency ncRNAs. This finding indicates that EBV is not the cause for the NK<unk>  activation and excessive proliferation seen in NKCE and LG and distinguishes these diseases from malignant diseases they can mimic such as extranodal NK/T-cell lymphoma, nasal type. In isolated reports, LG has occurred in individuals with Helicobacter pylori infection of the stomach or a history of stomach cancer, while NKCE has been reported to occur in patients with gluten sensitivity or circulating anti-gliadin antibodies. Both of the latter conditions are associated with the development of GI tract lymphomas. However, the relationship of any of these findings to the etiology of LB and NKCE is unclear.
Natural killer cell enteropathy
Autoimmune enteropathy
Environmental enteropathy
Congenital tufting enteropathy
Food protein-induced enterocolitis syndrome
Tropical sprue
Coeliac disease
Schnitzler syndrome