1Department of Immunology and Microbiology, School of Medicine, Molecular and Medicine Research Center
2Department of Surgery, School of Medicine
3Department of Epidemiology, School of Medicine, Arak University of Medical Sciences, Arak, Iran
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.