Stimulation of human T cells via anti-T cell receptor monoclonal antibody BMA031: distinct cellular events involving interleukin-2 receptor and lymphocyte function antigen 1

Transient combination therapy targeting the immune synapse abrogates T cell responses and prolongs allograft survival in mice

T cells play a major role in allograft rejection, which occurs after T cell activation by the engagement of several functional molecules to form an immune synapse with alloantigen presenting cells. In this study, the immune synapse was targeted using mAbs directed to the TCR beta-chain (TCRβ) and lymphocyte function-associated antigen−1 (LFA1) to induce long-term allograft survival. Evaluation of antigen-specific T cell responses was performed by adoptively transferring CFSE labeled transgenic OT-II cells into wild-type mice and providing OVA peptide by intravenous injection. Graft survival studies were performed in mice by transplanting BALB/c ear skins onto the flanks of C57BL/6 recipients. The anti-TCRβ plus anti-LFA1 mAb combination (but not either mAb alone) abrogated antigen-specific T cell responses invitro and invivo. Transient combination therapy with these agents resulted in significantly prolonged skin allograft survival in mice (51±10 days; p<0.01) when compared to treatment with either anti-TCRβ mAb (24±5 days) or anti-LFA1 mAb (19±3 days) alone or no treatment (10±1 days). When lymphoid tissues from these mice were analyzed at different times post-transplant, only those receiving the combination of anti-TCRβ and anti-LFA1 mAbs demonstrated long-lasting reductions in total T cell numbers, cellular and humoral anti-donor responses, and expression of CD3 on the surface of T cells. These results demonstrate that transient anti-TCRβ and anti-LFA1 mAb combination therapy abrogates antigen-reactive T cell responses with long-lasting effects that significantly prolong allograft survival.

ICAM-1-expressing pocket epithelium, LFA-1-expressing T cells in gingival tissue and gingival crevicular fluid as features characterizing inflammatory cell invasion and exudation in adult periodontitis

Activated T lymphocytes constitute a major component of inflammatory cells in the early periodontal lesion, and also appear in the gingival crevicular fluid. In an attempt to clarify the relationship between the ICAM-1 (CD54) expression of pocket epithelium in gingiva and the infiltrating lymphocyte population, we carried out an analysis of CD11a+(LFA-1 alpha), CD25+(IL-2R alpha) and CD4+(Th) cells subjacent to ICAM-1-expressing pocket epithelia and CD11a+CD25+CD4+ cells in gingival crevicular fluid (GCF). GCF was collected by crevicular washing from 16 patients with periodontitis (P group) and 3 subjects with healthy gingiva (H group). Peripheral blood (PB) was collected at the same time. Mononuclear cells were isolated by Ficoll-paque gradient centrifugation from GCF and PB. Monoclonal antibodies (mAb) to CD11a, CD25, and CD4 were used for three-color flow cytometry. Gingival biopsies were obtained from 7 patients in P group and 3 subjects in H group. Serial cryostat sections (6 microns in thickness) were prepared from each biopsy, on which a double staining was performed. The number of CD11a+CD25+CD4+ cells and the fluorescence intensity of FITC conjugated anti-CD11a were significantly higher in GCF than in PB (p < 0.001 to p < 0.01). CD11a+CD25+CD4+ cells were not detected in GCF in H group. The pocket epithelia expressed CD54 in P group, but not in H group. The number of CD11a+, CD25+ and CD4+ cells infiltrating the connective tissue subjacent to the upper, middle and lower parts of the CD54 positive pocket epithelium (n = 16) was 141 +/- 26, 38 +/- 13, 144 +/- 29 (cells/0.04 mm2), respectively, whereas in the CD54 negative pocket epithelium, it was (n = 5) 9 +/- 2, 3 +/- 1, 8 +/- 3. In P group, the CD11a+CD25+CD4+ cell number in GCF correlated with CD25+, CD11a+ cells in the connective tissue subjacent to the CD54+ pocket epithelium. These results indicate that expression of ICAM-1 in pocket epithelium is relevant to the migration of CD11a, CD25, CD4 positive cells in connective tissue subjacent to the pocket epithelium into the periodontal pocket. Assessing the relationship of our findings and other adhesion molecules would offer important clues to the understanding of T cell migration in affected gingiva.