Development and characterisation of T lymphocyte lines from human small intestinal biopsies

Intrinsic hyperreactivity of mucosal T cells to interleukin-2 in pediatric Crohn's disease

OBJECTIVES

To cells play a crucial role in many chronic inflammatory diseases. Mucosal T cells are particularly important in the pathogenesis of Crohn's disease (CD). We investigated the response of T cells in CD and other intestinal inflammatory conditions to interleukin-2 (IL-2), a cytokine essential for T-cell activation, growth, and function.

STUDY DESIGN

T-cell reactivity was assessed by measuring growth induced by IL-2 in mucosal endoscopic biopsy specimens obtained from children with CD, ulcerative colitis, indeterminate colitis, and chronic nonspecific colitis and from children without gastrointestinal inflammation.

RESULTS

CD mucosal T cells grew remarkably and significantly more than T cells from normal, ulcerative colitis, and chronic nonspecific colitis mucosa. T cells from indeterminate colitis mucosa grew similarly to those of CD mucosa. The enhanced growth response in CD was independent of disease location, presence or absence of intestinal inflammation, treatment, disease duration, or clinical activity.

CONCLUSION

Mucosal T cells from children with CD exhibit an intrinsic hyperreactivity to IL-2. This may represent a primary pathogenic abnormality in this condition.

Successful in vitro immortalization of human intestinal mucosal lymphocytes with Herpesvirus saimiri

Mucosal intestinal lymphocytes form the first immune-cell line of defense in the intestine. Several methodologies, most of them cumbersome and time consuming, have been used to obtain T-cell clones to unveil their physiological role. In the present work we take advantage of the recently described technique of transformation of T lymphocytes using Herpesvirus saimiri to show that it is possible to immortalize intestinal T-cell lines derived from healthy and diseased colonic samples and thence easily obtain in vitro intestinal T-cell lines as a model for physiopathological studies. Intestinal samples were obtained by colonoscopy and digested with dispase and collagenase. Mucosal lymphocytes (assessed by the expression of the CD3 and CD103 markers) were isolated using a Percoll gradient centrifugation and transformed with Herpesvirus saimiri. Sustained growth was observed 3 months later, showing that the cells were successfully transformed, a finding further confirmed by PCR. All cell lines were CD8+TcRalphabeta+ and HLA-DR+. CD25 was expressed on 1% of Crohn's disease-derived cells and on 25% of cells derived from patients with ulcerative colitis. CD80 expression was found on 80-90% of the cells. These immortal cell lines of intestinal origin may be useful in future experiments aimed at elucidating the role of mucosal lymphocytes in health and disease.

Phenotypic and immunoregulatory analysis of intestinal T-cells in patients with inflammatory bowel disease: evaluation of an in vitro model

Although a disturbed immune response to constituents of the gut mucosa has been implicated in the pathogenesis of inflammatory bowel disease, the mechanisms are still unclear. Intestinal T-cells derived from gut biopsies were propagated in vitro as single and co-cultures under different experimental conditions prior to flow cytometry. Intestinal T-cell lines from inflamed mucosa (n = 69) showed a significant (P < 0.001) decrease in CD4+ T-cells compared to T-cells from normal (n = 49) and uninflamed (n = 29) tissue specimens. Co-culturing of inflamed and uninflamed mucosa led to a normalization of CD4+ T-cells in cultures derived from inflamed mucosa. Analysis of supernatants revealed a significantly (P < 0.001) increased secretion of IL-4 under co-culture conditions. Moreover, stimulation of cultures derived from inflamed mucosa with rIL-4 led to a significant (P < 0.001) increase in CD4+ T-cells, whereas anti-IL-4 antibodies or IFN-gamma supplementation of T-cells derived from uninflamed mucosa significantly (P < 0.001) reduced the CD4+ subset. Treatment with IFN-gamma and anti-IL-4 antibodies did not affect the phenotype of T-cells derived from inflamed mucosa. These data suggest that IL-4 might play a key role in the intestinal immune response. Furthermore, this in vitro system allows the investigation of mucosal immune mechanisms in more detail under standardized conditions.

Phenotypic and functional characterization of T-cell lines generated from colonoscopic biopsy specimens in patients with ulcerative colitis

Intestinal T-cell lines were generated from lamina propria mononuclear cells isolated from colonoscopic biopsies in ulcerative colitis patients and controls. In both ulcerative colitis and controls, expanded cells were constituted largely by T-cell receptor alpha beta+, CD4+, CD45RA- (helper), and CD8+, CD11b- (cytotoxic) phenotypes. T-cell receptor V beta gene usage was not significantly changed after cell expansion and no difference was observed between ulcerative colitis and controls. Ulcerative colitis cells, especially those derived from the patients with long-standing disease, showed significantly higher levels of cytotoxicity against the target cells, including those of colonic epithelial origin, and enhanced production of tumor necrosis factor-alpha and interferon-gamma after short incubation with anti-CD3 antibody. Generation of T-cell lines from colonoscopic biopsy specimens may be useful for detailed functional characterization of locally infiltrating T cells in ulcerative colitis patients.