Background: The appendix is considered as part of the gut-associated lymphoid tissue; however, lymphocyte subsets in this tissue are not fully defined.
Objective: To investigate and compare the function and phenotype of lymphocyte subsets in peripheral blood and appendix of patients with normal and inflamed appendix tissues.
Methods: Peripheral blood samples and appendiceal mononuclear cells were obtained from 81 patients (mean age; 23 ± 10.5 years), clinically suspected of having appendicitis. The phenotypic characteristics of lymphocyte subsets in peripheral blood (before and 48-72 hrs after appendectomy) and in appendix tissue were analyzed by three color-flow cytometry. The proliferative response of mononuclear cells was assessed by MTT method.
Results: The frequency of CD19+DR+, HLA-DR+ and CD19+ cells in the appendix tissue were significantly higher than that of the peripheral blood in all the groups (p<0.001). The percentage of CD19+ cells and HLA-DR+CD19+ cells significantly decreased after appendectomy in the peripheral blood of the patients with acute appendicitis (p=0.047 and p=0.03, respectively). CD19 and HLA-DR plus CD19 had better diagnostic efficiency compared with T cell markers (area under the ROC curve [AUC]= 0.76 and 0.73, respectively).
Conclusion: These results indicate a significant difference in CD19+ and HLA-DR+ lymphocytes between peripheral blood and the appendix tissue.