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Keywords:

  • endothelial cells;
  • dendritic cells;
  • enteric antigens;
  • inflammatory bowel disease;
  • leukocyte homing;
  • T cell proliferation

Abstract

Introduction:

We have previously demonstrated that adoptive transfer of naïve CD4+ T cells devoid of lymphocyte function-associated antigen-1-deficient (LFA-1; CD11a/CD18) into recombination activating gene-1 (RAG-1) deficient (RAG−/−) mice fails to induce chronic colitis whereas transfer of wild type (WT) T-cells induces unrelenting and chronic disease.

Methods:

The objectives of this study were to assess the role of lymphocyte function-associated antigen-1 (LFA-1) in enteric antigen (EAg)-induced activation of T cells in vitro and in vivo and to define the importance of this integrin in promoting trafficking of T cells to the mesenteric lymph nodes (MLNs) and colon.

Results:

We found that EAg-pulsed dendritic cells (DCs) induced proliferation of LFA-1-deficient (CD11a−/−) CD4+ T cells that was very similar to that induced using WT T cells, suggesting that LFA-1 is not required for activation/proliferation of T cells in vitro. Coculture of WT or CD11a−/− T cells with EAg-pulsed DCs induced the generation of similar amounts of interferon-gamma, interleukin (IL)-4, and IL-10, whereas IL-17A production was reduced ≈2-fold in cocultures with CD11a−/− T cells. Short-term (20–22 hours) trafficking studies demonstrated that while both WT and CD11a−/− T cells migrated equally well into the spleen, liver, lungs, small intestine, cecum, and colon, trafficking of CD11a−/− T cells to the MLNs was reduced by 50% when compared to WT T cells. When the observation period was extended to 3–7 days posttransfer, we observed ≈2–3-fold more WT T cells within the MLNs and colon than CD11a−/− T cells, whereas T-cell proliferation (as measured by CFSE dilution) was comparable in both populations.

Conclusions:

Taken together, our data suggest that LFA-1 is not required for EAg-induced activation of CD4+ T cells in vitro or in vivo but is required for trafficking of T cells to the MLNs and homing of colitogenic effector cells to the colon where they initiate chronic gut inflammation. (Inflamm Bowel Dis 2012;)