Expression of the Kp43 (CD 94) receptor by natural killer (NK) cells in ulcerative colitis

Background/Aims: The presence of natural killer cells in the colon mucosa o f patients with ulcerative colitis, has not been studied, therefore, the st udy was designed to investigate the densities of cells expressing CD3+, CD4 +, CD8+, CD56+ and the new CD94+ in colon mucosa of active and inactive ulc erative colitis patients. Methodology: Twenty ulcerative colitis patients, 10 with active disease and 10 with inactive disease, and 10 subjects with a histologically normal rec tal mucosa were used as patients and controls. Additionally, a subgroup of 6 patients with active proctitis has been studied. Two biopsy specimens fro m rectal mucosa were taken for all patients and controls. Two biopsy specim ens of proximal colon mucosa of the subgroup of 6 patients were also taken. One biopsy was processed for immunohistochemical studies and another for h istologic study. Results: The densities of CD3+, CD16+, CD56+ and CD 94+ were significantly increased in active ulcerative colitis patients compared to inactive subjec ts (P < 0.001). The increase in the CD4+ and CD8+ was not statistically sig nificant. Patients with inactive ulcerative colitis also presented increase d numbers of CD3+, CD56+ and CD94+ cells compared to controls (P < 0.001). In the subgroup of proctitis, the densities of cells expressing all the ant igens were significantly lower in the normal mucosa compared to the affecte d colon (P < 0.001). No differences in the number of lamina propria DC1a+ c ells between patients and controls were found. Conclusions: These findings suggest that natural killer cells are increased in active ulcerative colitis subjects and that the affected mucosa of ulce rative colitis patients with inactive disease is in state of "latent" infla mmation. On the other hand, the normal looking mucosa from active ulcerativ e colitis patients does not differ from the mucosa of control subjects. The refore, it seems that in ulcerative colitis the immunological alterations a re limited to the affected mucosa.