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Phenotypic pattern of B cells in the appendix: reduced intensity of CD19 expression
E Somekh1, F Serour, A Gorenstein
1Pediatric Infectious Diseases and Immunology Unit, Edith Wolfson Medical Center, Holon, Israel. esomeh@post.tau.ac.il
Insights
The appendix contains more B cells, including B1 cells, than peripheral blood, suggesting a role in the immune response to appendicitis. Appendiceal B cells show unique CD19 expression.
Area of Science:
- Immunology
- Cell Biology
Background:
- The appendix is part of the gut-associated lymphoid tissue (GALT).
- Understanding the appendix's immunological role is crucial for GALT research.
Purpose of the Study:
- To analyze the cellular composition of normal and inflamed human appendix tissue.
- To investigate the expression of CD19 and CD5 markers on B cells within the appendix.
Main Methods:
- Flow cytometry was used to analyze cellular composition.
- Samples included peripheral blood, appendiceal vein blood, omentum, and peritoneal fluid.
- Study involved 17 pediatric patients undergoing appendectomy.
Main Results:
- The appendix has a higher percentage of CD19+ and B1 cells compared to peripheral blood.
- CD19 staining intensity is decreased on appendiceal and omental lymphocytes.
- Inflamed appendices show a higher proportion and ratio of B1 cells.
Conclusions:
- The appendix harbors a distinct B cell population, with elevated B1 cells, involved in immune responses.
- Appendiceal B cells exhibit unique CD19 surface expression patterns.
Unlabelled:
The lymphoid tissue of the appendix is considered as part of the gut-associated lymphoid tissue (GALT). In order to understand better the immunological significance of the appendix we analyzed the cellular composition of normal and inflamed human appendix tissue by flow cytometer with special attention to expression of the CD19 and CD5 markers on B cells. Cellular analysis was also performed on peripheral and appendical vein blood samples as well as on omentum and peritoneal fluid samples. The study population included seventeen patients aged 2-15 yr. (mean age - 11.5 yr.) undergoing appendectomy. Ten children were diagnosed with acute appendicitis while 7 had a normal appendix.
Results:
Compared to the peripheral blood, the appendix contained a significantly higher percentage of CD19 cells (47.6% of total lymphocytes versus 15%, p<0.0001), and B1 cells (4.98% of total lymphocytes versus 2.42%, p=0.001). In addition, the intensity of CD19-staining was markedly decreased in the appendix (mean - 395.7), and also in the omentum (mean - 398.2) as compared to peripheral lymphocytes (mean - 497.7, p<0.0001 for both comparison). Comparison between the inflamed and the non-inflamed appendices revealed that the inflamed appendix contained a significantly higher proportion of B1 cells (5.64% of total lymphocytes versus 3.53%, p=0.032), and also a higher B1/b cell ratio (0.13 vs. 0.07, p=0.01).
Conclusions:
These results indicate that the appendix tissue contains higher number of B1 (and B) cells compared to the peripheral blood and that these cells play a role in the primary immune response to acute infection/inflammation in the appendix. Appendiceal B cell population is unique in term of CD19 intensity expression on their surface.
