Feasibility of Flow Cytometry Analysis of Gastrointestinal Tract-Residing Lymphocytes in Hematopoietic Stem Cell Transplant Recipients.

The feasibility of lymphocyte isolation and flow cytometry using a single endoscopic biopsy specimen from the gastrointestinal tract of patients who have undergone hematopoietic stem cell transplantation has not been investigated. We acquired 51 endoscopic biopsy specimens from the gastrointestinal tract of 35 patients. We divided the flow cytometry samples into two groups: group A, successful lymphocyte isolation (n=24), and group B, incomplete isolation (n=27). We compared the backgrounds of the samples between the groups to reveal crucial elements in the successful isolation of lymphocytes residing in the gastrointestinal tract. Comparison between the groups revealed lymphocyte isolation success rates differed between biopsy sites. Isolation was most successful in samples from the duodenum (8/9, 88.9%), followed by the ileum (4/8, 50.0%), large intestine (4/11, 36.4%), and stomach (8/23, 34.8%). Tacrolimus was used more frequently in group B (92.6%) than in group A (62.5%) (p=0.015). Logistic regression analysis revealed that isolation from the duodenum or ileum was a significant factor for successful isolation, while tacrolimus use was not statistically significant. In conclusion, the duodenum and ileum are more suitable sites than the stomach and colorectum for acquiring samples for flow cytometry.

Characterization of Gastric Tissue-Resident T Cells in Autoimmune and Helicobacter pylori-Associated Gastritis.

Data regarding the in-depth surface marker profiles of gastric tissue-resident lymphocytes in autoimmune and Helicobacter pylori-associated gastritis are lacking. In this study, we investigated potential differences in lymphocyte composition between these profiles. We enrolled patients with autoimmune (n = 14), active (current infection of H. pylori in the stomach; n = 10), and inactive gastritis (post-eradication of H. pylori; n = 20). Lymphocytes were isolated from the greater curvature of the stomach and lesser curvature of the body and analyzed using flow cytometry. The CD8+/CD3+ and CD4+/CD3+ ratios differed between the samples. Body CD4+/antrum CD4+, which is calculated by dividing the CD4+/CD3+ ratio in the body by that in the antrum, was significantly higher in autoimmune gastritis (3.54 ± 3.13) than in active (1.47 ± 0.41) and inactive gastritis (1.42 ± 0.77). Antrum CD8+/CD4+ in autoimmune gastritis (7.86 ± 7.23) was also higher than that in active (1.49 ± 0.58) and inactive gastritis (2.84 ± 2.17). The area under the receiver operating characteristic curve of antrum CD8+/CD4+ was 0.842, and the corresponding optimal cutoff point was 4.0, with a sensitivity of 71.4% and a specificity of 93.3%. We propose that an antrum CD8+/CD4+ ratio > 4.0 is a potential diagnostic marker for autoimmune gastritis.

Increased CCR4+ and Decreased Central Memory CD4+ T Lymphocytes in the Background Gastric Mucosa of Patients Developing Gastric Cancer After Helicobacter pylori Eradication: An Exploratory Study.

The composition of lymphocytes in the gastric mucosa following the eradication of Helicobacter pylori (H. pylori) in patients with and without gastric cancer has not been compared. This study performed a single spot analysis of gastric mucosal lymphocytes after H. pylori eradication in patients with (n = 13) and without (n = 20) gastric cancer. Our comprehensive analysis of lymphocyte composition in the gastric mucosa revealed that: i) the proportion of CD8+/CD3+ cells was relatively higher in the peri-tumor mucosa than in the background mucosa; ii) the proportion of CCR4+/CD3+ cells was higher, and the ratio of CD62L+/CD3+CD4+ cells was relatively lower in the gastric mucosa of cancer patients than in non-cancer patients; and iii) the proportion of CD45RA-CD62L+/CD3+CD4+ cells, namely, the central memory CD4+ T-cell fraction, was lower in the gastric mucosa of cancer patients than in non-cancer patients. Although the exact mechanism of the altered proportions of CCR4+/CD3+ and central memory CD4+ cells in the gastric mucosa of patients with cancer is unknown, focusing on lymphocytes in the gastric mucosa might help improve our understanding of gastric cancer development after H. pylori eradication.