BACKGROUND: A deficiency of gammadelta T cells has been described in Crohn's disease (CD). AIM: To analyze the gene expression of interleukin 7 (IL-7) and its receptors in the tissues of patients with CD. METHODS: We studied the peripheral blood of 80 patients with CD, comparing them with a group of 80 healthy subjects. The number and apoptosis of alphabeta and gammadelta T cells in peripheral blood and the proportion of alphabeta and gammadelta T cells in the intestinal tissues of patients with CD (n = 25) were studied. The gene and protein expression of IL-7, IL-2 receptor subunit gamma [cluster of differentiation 132 (CD132)], receptor alpha (CD127), and caspase-3 in tissues was analyzed by quantitative PCR. Serum IL-7 levels were also analyzed. RESULTS: In patients with CD, a decreased number of gammadelta T cells and an increase in the apoptosis of CD56+ alphabeta and gammadelta T cells in peripheral blood was observed (P < 0.0001 and P < 0.01) respectively, and there was an inverse correlation among T subsets and their apoptosis. In addition, IL-7 gene expression and IL-7 protein in the tissues of these patients were increased. The titers of caspase-3 in tissues were low vs control group (P > 0.01). The percentage of CD8+gammadelta T cells decreased in tissues (P < 0.01), and was directly related to IL-7 levels in peripheral blood. The expression of IL-2 receptor subunit gamma (CD132) was greatly decreased in the tissues of patients with CD (P < 0.05). CONCLUSION: There may be a cause-effect relationship between the lower gene expression of the IL-2 receptor subunit gamma (CD132) in tissues of patients with CD and gammadelta T cells immunodeficiency.