Elsevier

Transplant Immunology

Volume 8, Issue 3, November 2000, Pages 203-209
Transplant Immunology

Transgenic anti-CD4 monoclonal antibody secretion by mouse segmental pancreas allografts promotes long term survival

https://doi.org/10.1016/S0966-3274(00)00028-9Get rights and content

Abstract

To compare the effectiveness of transgenic and systemic monoclonal antibody therapy for pancreas transplantation, vascularised segmental pancreas allografts from wild-type or transgenic pancreatic tissue that secreted monoclonal anti-CD4 were placed in CBA recipients in which diabetes had been induced chemically by streptozotocin (STZ, non-autoimmune diabetes). In untreated CBA recipients, wild-type BALB/c or C57BL/6 bm1 pancreas transplants were rejected in a mean survival time (MST) of 27 and 30 days, respectively. BALB/c and C57BL/6 graft survival improved when recipients were given a short course of T cell depleting monoclonal anti-CD4 antibody, (GK 1.5, 2 mg total on days –1, 0, 1, 2 with grafting on day 0) with MST±S.D. of 71±29 and 44±36 days, respectively. Thus, transient depletion of CD4 was effective in delaying pancreas allograft rejection in these strain combinations. The use of C57BL/6 bm1 mice transgenic for a rat anti-CD4 antibody (GK5 mice) as pancreas donors provided allografts that secreted sufficient anti-CD4 antibody to cause CD4 T cell depletion in the recipients (CD4 cells decreased from 30 to <5% of small lymphocytes). This degree of depletion was not sustained and the CD4 recovery inversely correlated with graft survival. Mice with >20% CD4 cells in the splenic lymphocyte population 4 weeks post-transplant rejected their grafts (3 of 10 mice). However, in 7 of 10 mice CD4 cells remained low (<15%) and allografts survived for >80 days. The GK5 allografts survived significantly longer than those from non-transgenic bm1 controls (MST 83±32 days, compared with 30 days, P<0.0005). This survival time was similar to that of BALB/c allografts in CBA recipients treated with a high dose of anti-CD4 antibody. Thus, transgenic secretion of anti-CD4 antibody by the pancreas allograft was very effective in prolonging its survival.

Introduction

Although Type 1 diabetes can be successfully treated with insulin therapy, only pancreas or islet transplantation can permanently cure patients and prevent the end-stage organ failure often associated with long term diabetes. The results for pancreas transplantation have improved dramatically in the last 10 years, with the 1 year survival rate for pancreas plus kidney transplants now equivalent to that of kidney transplants alone [1]. However the results for pancreas only transplants, which could prevent renal failure and vascular disease, still lag behind, with 15% graft loss due to rejection occurring at 1 year compared with 2% for simultaneous kidney plus pancreas transplants [1]. Current research to improve pancreas grafts centres on the supply of islet tissue [2] and immunosuppression that is less toxic to islet tissue [3]. The problems of developing immunosuppression to combat both T cell-mediated autoimmune responses and allograft rejection apply to whole and segmental pancreas transplantation and to islet cell replacement [4]. CD4 T cells have been shown to play a central role in the rejection of both pancreas allografts and xenografts placed under the kidney capsule in mice [5], [6]. Clinical results suggest that anti-CD4 antibody may be more effective and less toxic than anti-CD3 as an immunosuppressive agent for pancreas transplantation [1]. Our previous studies in STZ-induced diabetic mice have shown prolonged survival of vascularised pancreas allografts in mice treated with either anti-lymphocyte serum or anti-CD4 antibody [7]. Thus, we have used a segmental pancreas allograft model in the mouse to compare the effects of transgenic delivery of anti-CD4 antibody with systemic injection of monoclonal antibody at the time of transplant only. This transplant model provides immediate results in that recipient blood glucose levels return to normal within hours when transplants are successful [7]. The recently established line of transgenic mice expressing a rat anti-CD4 antibody (GK2c) have sustained secretion of anti-CD4 antibody from the pancreatic islets and acinar tissue [8]. Transgenic delivery of anti-CD4 antibody provides a secreted immunosuppressive product within the graft, a delivery system that has proved effective in other studies for CTLA4Ig [9], [10] and a method that may be applicable in future to genetically modified islet xenotransplantation.

Section snippets

Objectives

Treatment with the immunosuppressive antibody GK1.5 specific for CD4 T cells is known to be effective in prolonging islet and pancreas allograft survival in the mouse [5], [7]. Since low dose, locally delivered immunosuppression has been reported to be more effective than systemically delivered treatment [11], our aim was to investigate the immunosuppressive effects of transgenic anti-CD4 secreted in situ by the pancreas allograft and to compare this with anti-CD4 delivered by i.p. injection.

Mice

CBA (H-2k) were used as pancreas recipients. BALB/c (H-2d), bm1 (H-2b/bm1) C57Bl/6 (H-2b) and GK5 (H-2b/bm1) mice were used as donors. Mice transgenic for a rat anti-mouse CD4 antibody have been described previously [8]. The entire κ light chain of GK1.5 was used. The V-region and first half of the CH1 region was fused to the latter half of the CH1, hinge, CH2 and CH3 regions of mouse IgG2c. These donor mice had no peripheral CD4 T cells [8]. Recipient mice were treated with a single i.v.

Statistics

Mean survival times (MST) were compared between different groups of pancreas grafts by multiple analysis of variance without replication (ANOVA, StatView 4.5, Abacus Concepts, Inc., Berkeley, CA, USA). If the ANOVA was significant, individual comparisons were made by the Student's t-test and the level of significance was corrected by the Bonferroni method [16].

Long-term pancreas allograft survival in anti-CD4 antibody-treated diabetic mice

Pancreas survival data are summarized in Table 1. BALB/c pancreas grafts to untreated CBA mice survived for a mean of 27 days. Survival of bm1 allografts in untreated CBA mice was similar to that of BALB/c allografts (MST 30 days compared with 27 days, P=0.8). This was to be expected since both allografts were fully MHC mismatched. Wild-type C57BL/6 (H-2b) to CBA grafts showed inconsistent improvement in graft survival (MST=44±35 days, P>0.05 compared with untreated controls) while BALB/c

Discussion

Although T cell-mediated acute rejection has been studied in detail in allografts, where the host immune system was modified by anti-CD4 antibody treatment of the recipients to allow graft survival [17], [18], [19], transgenic technology offers the exciting possibility of modifying the donor tissue to provide its own immunosuppression. The findings presented here show that transgenic expression of a chimeric anti-CD4 antibody (GK2c) within a transplanted organ can protect the allograft from

Acknowledgements

PLM, W-RH and LM-S were supported by the National Heart Foundation of Australia and the National Health and Medical Research Council of Australia (NHMRC). YZ was funded by the JDFI-NIH Angelo and Susan Alberti program grant and grants from Diabetes Australia. AML and JLB were funded by NHMRC.

We thank Steven Mihajlovic and Ellen Tsui for assistance with histology and Fleur Rodda and Michelle Latimer for assistance with mouse maintenance. We also thank Ms Julie Maguire (Monash Medical School,

References (32)

  • W. Han et al.

    Assessment of peripheral tolerance in anti-CD4 treated C57BL/6 mouse heart transplant recipients

    Transplant Immunol

    (1999)
  • T.E. Mandel et al.

    The effect of a depleting anti-CD4 monoclonal antibody on T cells and fetal pig islet xenograft survival in various strains of mice

    Transplant Immunol

    (1995)
  • H. Auchincloss et al.

    Pancreas transplantation & commentary

  • T.E. Mandel et al.

    A comparison of organ cultured fetal pancreas allo-, iso-, and xenografts (pig) in non-immunosuppressed non-obese diabetic mice

    Am J Pathol

    (1995)
  • J. Sandberg et al.

    Toxicity in vivo to different immunosuppressive drugs in fetal porcine pancreatic islets

    Transplantation

    (1996)
  • B. Steiniger et al.

    Identical pattern of acute rejection after isolated islet and vascularised whole pancreas transplantation in the rat

    Am J Pathol

    (1990)
  • K. Burkhardt et al.

    An increase in the survival of murine H-2 mismatched cultured fetal pancreas allografts using depleting or nondepleting anti-CD4 monoclonal antibodies and a further increase with the addition of cyclosporine

    Transplantation

    (1989)
  • C. Simeonovic et al.

    Immune mechanisms associated with the rejection of fetal murine proislet allografts and pig proislet xenografts: comparison of intragraft cytokine mRNA profiles

    Transplantation

    (1999)
  • L.J. Purcell et al.

    Immunosuppressive antibody treatment prolongs graft survival in two murine models of segmental pancreas transplantation

    Immunol Cell Biol

    (1993)
  • W.R. Han et al.

    Prolonged allograft survival in anti-CD4 transgenic mice: lack of helper T cells compared with other CD4 deficient mice

    Transplantation

    (2000)
  • Z. Yang et al.

    Cardiac allograft tolerance induced by intra-arterial infusion of recombinant adenoviral CTLA4Ig

    Transplantation

    (1999)
  • A.M. Lew et al.

    Secretion of CTLA4Ig by an SV40 T antigen-transformed islet cell line inhibits graft rejection against the neoantigen

    Transplantation

    (1996)
  • S. Stepkowski et al.

    Prolongation of heterotopic heart allograft survival by local delivery of continuous low-dose cyclosporine therapy

    Transplantation

    (1989)
  • R. Pollack et al.

    Resolution of streptozotocin-induced diabetes mellitus by pancreatic transplantation in the mouse

    Transplantation

    (1988)
  • D.P. Dialynas et al.

    Characterization of the murine T cell surface molecule, designated L3T4, identified by monoclonal antibody GK1.5: similarity of L3T4 to the human Leu-3/T4 molecule

    J Immunol

    (1983)
  • P. Mottram et al.

    Long-term survival of segmental pancreas isografts in NOD/Lt mice treated with anti-CD4 and anti-CD8 monoclonal antibodies

    Diabetes

    (1998)
  • Cited by (4)

    • Combination of monoclonal antibodies and DPP-IV inhibitors in the treatment of type 1 diabetes: A plausible treatment modality?

      2014, Medical Hypotheses
      Citation Excerpt :

      Successful results using insulin therapy remains inadequate. In fact, T1D is reversed by islet transplantation; nevertheless, it is associated with the surgical morbidity and hostile effects of persistent immune suppression [5]. The body often destroys transplanted islet cells owing to MHC of host identifying the graft tissue as foreign antigens and attacking them.

    • Ultrasound-Enhanced Monoclonal Antibody Production

      2012, Ultrasound in Medicine and Biology
      Citation Excerpt :

      Anti-CD4 mAb has been used to treat many autoimmune disorders, including acute and relapsing experimental allergic encephalomyelitis (EAE) (Sriram et al. 1988) and chronic eosinophilic lung inflammation (Doherty et al. 2009). It has been used as immunosuppressive agent for prolonging islet and pancreas allograft survival in mouse models (Mottram et al. 2000). Anti-CD4 mAb is also widely used in immunologic and transplantation laboratories for studying autoimmune disorders.

    View full text