BACKGROUND AND OBJECTIVES: gamma delta T cell populations are well-known for their unique distribution (e.g. intra-epithelial lymphocytes). Though their ligands play a major role in the immune response they have remained largely obscure. To shed light on this issue, we have analyzed in this study the complementarity determining region (CDR) 3 of the T cell receptor (TCR) V delta 2 chains. This provides an insight into the antigenic immune response in the intestinal mucosa in sickness and health. METHODOLOGY: Total RNA was extracted from surgically resected intestinal mucosa of patients with Crohn's disease (CD) and controls. TCR V delta 2 cDNA was PCR-amplified using V delta 2 sense primer and C delta antisense primer. The PCR products were then subcloned in pUC18 plasmid. From each sample, 20 subclones were randomly selected and subjected to nucleotide sequence analysis. RESULTS: Sequence analysis revealed that the CDR3 sequences of the TCR V delta 2 chains were unique to each individual. The evidence also showed a significant restriction of the junctional diversity of the TCR V delta 2 chains while no such restriction was found for CD. CONCLUSIONS: The marked complexity of the TCR V delta 2 junctional sequences and the oligoclonality of the TCR V delta 2 genes in the control subjects are indicative of a positive selection and expansion of specific T cells in the normal, healthy condition. In CD patients, however, the expression of distinct, non-overlapping TCR V delta 2 clonotypes can be found, suggesting polyclonal activation of gamma delta T cells in the diseased colon of CD patients. These findings have led us to conclude that accumulation of multiple gamma delta T cell clonotypes may be involved in the pathogenesis of CD. Copyright 2001 S. Karger AG, Basel
BACKGROUND AND OBJECTIVES: gamma delta T cell populations are well-known for their unique distribution (e.g. intra-epithelial lymphocytes). Though their ligands play a major role in the immune response they have remained largely obscure. To shed light on this issue, we have analyzed in this study the complementarity determining region (CDR) 3 of the T cell receptor (TCR) V delta 2 chains. This provides an insight into the antigenic immune response in the intestinal mucosa in sickness and health. METHODOLOGY: Total RNA was extracted from surgically resected intestinal mucosa of patients with Crohn's disease (CD) and controls. TCR V delta 2 cDNA was PCR-amplified using V delta 2 sense primer and C delta antisense primer. The PCR products were then subcloned in pUC18 plasmid. From each sample, 20 subclones were randomly selected and subjected to nucleotide sequence analysis. RESULTS: Sequence analysis revealed that the CDR3 sequences of the TCR V delta 2 chains were unique to each individual. The evidence also showed a significant restriction of the junctional diversity of the TCR V delta 2 chains while no such restriction was found for CD. CONCLUSIONS: The marked complexity of the TCR V delta 2 junctional sequences and the oligoclonality of the TCR V delta 2 genes in the control subjects are indicative of a positive selection and expansion of specific T cells in the normal, healthy condition. In CDpatients, however, the expression of distinct, non-overlapping TCR V delta 2 clonotypes can be found, suggesting polyclonal activation of gamma delta T cells in the diseased colon of CDpatients. These findings have led us to conclude that accumulation of multiple gamma delta T cell clonotypes may be involved in the pathogenesis of CD. Copyright 2001 S. Karger AG, Basel