en Gastroentrology Gastroentrology Original Article Original Article <span style="font-size:14px;"><span style="font-family:times new roman;"><span style="color:#0000FF;"><strong><em>Background</em></strong><em>:</em></span> Functional dyspepsia (FD) is the most common gastrointestinal disorder with several symptoms such as stomach pain and abdominal bloating. The aim of this study was to investigate and compare CD4+ and CD8+ in the Helicobacter pylori-negative functional dyspepsia and control groups.<br> <span style="color:#0000FF;"><strong><em>Methods</em></strong><em>:</em> </span>Sixty one patients (35 patients with stomach pain and 26 with abdominal bloating), and 30 controls were reviewed based on the quantity of CD4+ and CD8+ T-cells isolated from gastric mucosa biopsy samples. The comparison between variables was analyzed with a chi-square or Fisher&rsquo;s exact test and logistic regression analyses. P<0.05 and odds ratio (OR) with a 95% confidence interval demonstrated statistical significance.<br> <span style="color:#0000FF;"><strong><em>Results:</em></strong></span> A significant difference was observed between two-group patients and control group based on CD4+ and CD8+ presence, respectively (P=0.003, P=0.008). Furthermore, there was a significant difference between stomach pain-patients and control group with regard to&nbsp;CD4 count (P=0.01) and between abdominal bloating-patients and control group with regard to&nbsp;CD8 count (P=0.002). There was a decrease in both CD4+ and CD8+ T-cells in gastric mucosa in patients with FD with a significant reduction in the stomach pain-patients and abdominal bloating-patients in the number of CD4+ and CD8+ T-cells, respectively.<br> <span style="color:#0000FF;"><strong><em>Conclusion</em></strong><em>:</em></span> These results indicated that the role of immunology in the absence of the CD4+ and CD8+ T-cells in the gastric mucosa may have a protective role against FD.</span></span> Functional dyspepsia, Comparison, T-lymphocytes, Helicobacter pylori, CD4, CD8. 150 154 http://caspjim.com/browse.php?a_code=A-10-1446-1&slc_lang=en&sid=1 Leila Vahedi Vahedi.l49@gmail.com 100319475328460021738 100319475328460021738 Yes Liver and Gastrointestinal Disease Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran. Sousan Mirnajd Gerami smirnajd@gmail.com 100319475328460021739 100319475328460021739 No Kourosh Masnadi-Shirazi KURMAS23@yahoo.com 100319475328460021740 100319475328460021740 No Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Seyed Kazem Mirinezhad mirinezhad@gmail.com 100319475328460021741 100319475328460021741 No Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Shabnam Salehi salehi.sh@yahoo.com 100319475328460021742 100319475328460021742 No Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Monireh Halimi mohalimi@gmail.com 100319475328460021743 100319475328460021743 No Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran