Impact of Antimouse CD52 Monoclonal Antibody on Graft’s γδ Intraepithelial Lymphocytes After Orthotopic Small Bowel Transplantation in Mice

Abstract

Alemtuzumab, a humanized CD52 monoclonal antibody (mAb), has been used for immune induction in clinical small bowel transplantation (SBT). However, the local impact of CD52 mAb on the transplanted intestine is not known. In this study, we investigated the effects of CD52 mAb on the intestinal intraepithelial lymphocytes (iIELs) in grafts using a murine orthotopic SBT model. The antimouse CD52 mAb was used as a surrogate antibody. Graft rejection was assessed by histopathologic analysis, iIELs were isolated for flow cytometric analysis, the mucosal keratinocyte growth factor (KGF) expression was evaluated by real-time polymerase chain reaction, and epithelial cell (EC) proliferation (percent bromodeoxyuridine incorporation) was measured by immunohistochemistry. No mice showed evidence of rejection. Seven days after SBT, when the CD52 mAb was used, the numbers of iIELs and both T-cell receptor (TCR) γδ and TCRαβ subpopulations were decreased, and the number of TCRγδ iIELs of donor origin was prominently reduced in the allografts. Furthermore, TCRγδ iIEL-derived KGF messenger RNA expression and EC proliferation decreased significantly after CD52 mAb application. These data demonstrate that the antimouse CD52 mAb could deplete iIELs in the transplanted intestine, especially the TCRγδ subset of donor origin. The reduction of TCRγδ iIELs accompanied the decrease in mucosal KGF expression and EC proliferation, which may slow down the epithelial turnover and retard the repair of the damaged epithelium.

Tissue‐resident T cells, in situ immunity and transplantation

“…Lymphocyte ablation, using thymoglobulin or alemtuzumab (Campath‐1H), is performed within hours before organ transplantation with detectable levels of the monoclonal antibody detectable in circulation at the end of the first postoperative week. The effect of the induction therapy on donor passenger cells is not clearly known; however, a murine orthotopic small bowel transplantation model revealed that alemtuzumab significantly depleted donor T cells within the lamina propria and intraepithelial compartment of the transplanted graft . In this mouse model, both γδ and αβ T cells were reduced in the gut after treatment with alemtuzumab.…”

“…In this mouse model, both γδ and αβ T cells were reduced in the gut after treatment with alemtuzumab. At 2 weeks posttransplantation, most γδ TCR + cells within the intraepithelial compartment were of host origin along with significant repopulation by host‐derived ‐αβ T cells . Lymphocyte ablation might therefore cause a period of lymphopenia within the allograft (of gut Trm cells), or it may increase the kinetics of repopulation of the allograft.…”

Deciphering the Contribution of γδ T Cells to Outcomes in Transplantation

“…Again, γδ T cells produced a Th2-like cytokine phenotype through production of IL-4, IL-10 and TGFβ 159. Administration of the monoclonal antibody anti-CD52 (alemtuzumab) prominently depletes the donor-derived γδTCR + iEL compartment in a mouse model of small bowel transplantation 160…”