Article Text
Abstract
Background: Inflammatory bowel disease in interleukin 2 (IL-2) deficient (IL-2−/−) mice is triggered by the intestinal microflora and mediated by CD4+ T cells.
Aims: To determine the characteristics of microflora specific intestinal T cells, including migration and cytokine production.
Methods: Intestinal T cell populations and cytokine mRNA expression of specific pathogen free (SPF) and germ free (GF) IL-2−/− and IL-2+/+ mice were compared by flow cytometry and reverse transcription-polymerase chain reaction. Cytokine production of intestinal mononuclear cells on stimulation with microflora antigens was assessed by ELISA. In vivo migration of T cells was assessed by adoptive transfer of 51Cr labelled CD4+CD25−αβ+ T cells. The ability of intestinal T cell lines to promote colitis was determined by adoptive transfer experiments.
Results: SPF IL-2−/− mice produced higher interferon γ (IFN-γ) and tumour necrosis factor α mRNA levels than GF IL-2−/− mice, which was accompanied by an increased number of CD4+αβ T cells in the colon. Tracking of 51Cr labelled and adoptively transferred T cells revealed an increased MAdCAM-1 dependent but VCAM-1 independent recruitment of these cells into the colon of SPF IL-2−/− mice. Colon lamina propria lymphocytes (LPL) from SPF IL-2−/− mice showed increased spontaneous IFN-γ production in vitro. On stimulation with bacterial microflora antigens, intraepithelial lymphocytes and LPL did not produce IFN-γ, but high quantities of IL-10, which did not suppress IFN-γ production. Bacterial antigen specific cell lines established from colon LPL of SPF IL-2−/− mice with colitis showed a regulatory T cell-like cytokine profile and only marginally modulated the course of colitis and survival of IL-2−/− mice.
Conclusions: Our results suggest that microflora reactive regulatory T cells are present in the colon of SPF IL-2−/− mice. However, IL-10 produced by these cells did not significantly modulate a possible secondary proinflammatory CD4 Th1 cell population to produce IFN-γ.
- cytokines
- mice
- migration
- microflora
- T cells
- IBD, inflammatory bowel disease
- IL, interleukin
- TNF-α, tumour necrosis factor α
- IFN-γ, interferon γ
- DEPC, diethyl-pyrocarbonate
- dNTP, deoxynucleoside triphosphate
- IEL, intraepithelial lymphocytes
- LPL, lamina propria lymphocytes
- GF, germ free
- SPF, specific pathogen free
- GALT, gut associated lymphoid tissue
- PCR, polymerase chain reaction
- RT, reverse transcription
- BSS, Hank's balanced salt solution
- PBS, phosphate buffered saline
- mAbs, monoclonal antibodies
- CBA, caecal bacterial antigen
- Tr1, regulatory T cells
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- IBD, inflammatory bowel disease
- IL, interleukin
- TNF-α, tumour necrosis factor α
- IFN-γ, interferon γ
- DEPC, diethyl-pyrocarbonate
- dNTP, deoxynucleoside triphosphate
- IEL, intraepithelial lymphocytes
- LPL, lamina propria lymphocytes
- GF, germ free
- SPF, specific pathogen free
- GALT, gut associated lymphoid tissue
- PCR, polymerase chain reaction
- RT, reverse transcription
- BSS, Hank's balanced salt solution
- PBS, phosphate buffered saline
- mAbs, monoclonal antibodies
- CBA, caecal bacterial antigen
- Tr1, regulatory T cells