Intrathymic inoculation of donor B cells induced indefinite prolongation of fully allogeneic cardiac grafts but not islet or skin grafts

Intrathymic Inoculation of Donor B Cells Induced Indefinite Prolongation of Fully Allogeneic Cardiac Grafts but Not Islet or Skin Grafts M. Niimi, Y. Ikeda, N. Shirasugi, T. Shatari, H. Takami, S. Kodaira, K. Matsumoto, K. Hamano, K. Esato, and K.J. Wood

I

NTRATHYMIC administration of donor resting B cells has been shown to be more effective at inducing indefinite survival of fully allogeneic cardiac grafts when delivered with depleting anti-CD4 monoclonal antibody (mAb).1 Therefore, we examined whether intrathymic administration of donor B cells could also induce survival of pancreatic islet or skin allografts. MATERIALS AND METHODS Treatment CBA (H2k) mice were injected with 1 ⫻ 106 donor resting B cells intrathymically (day ⫺27) in the presence of depleting anti-CD4 mAb, (YTA 3.1.2, 50 ␮g/dose, day ⫺28 and ⫺27). These mice were transplanted with hearts, skin, or pancreatic islet from C57BL/10 (H2b) mice. Heart grafting, skin transplantation, and thymectomy were performed as described previously.1,2

B Cell Preparation B cells were made by antibody-complement lysis, Sephadex G-10 column, and Percoll gradient. A typical preparation of B cells as analysed by flow cytometry was found to be 95.7% major histocompatability complex class II⫹, 1.2% CD80⫹, 2.5% CD86⫹ and 92.3% sIg⫹.

Islet Transplantation Diabetes was induced using a single intravenous dose of streptozotocin (250 mg/kg, Sigma), and blood glucose levels were monitored regularly. Only those animals with blood glucose levels greater than 20 mmol/mL were used as recipients. Islets were isolated using collagenase digestion of the pancreas followed by centrifugation through a discontinuous Ficoll gradient. Diabetic mice underwent a median laparotomy, the left kidney was visualised, and a subcapsular pocket was developed. Approximately 800 freshly isolated islets, which had been previously mixed with a single drop of autologous blood, were placed under the renal

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capsule. Transplanted animals with three consecutive blood glucose levels greater than 12.5 mmol/L were considered to have rejected their islet grafts.3

RESULTS

Indefinite prolongation of C57BL/10 cardiac grafts was induced in CBA mice pretreated with intrathymic injection of donor B cells and anti-CD4 mAb. Mice pretreated with B cells alone or anti-CD4 mAb alone rejected their grafts acutely (MSTs ⫽ 8 and 10 days, respectively). Next, mice were pretreated with B cells and anti-CD4 mAb and then transplanted with C57BL/10 pancreatic islet or skin grafts. In contrast to cardiac grafts, islet and skin grafts were rejected acutely (MST ⫽ 9.5 and 16.5 days, respectively). CONCLUSION

Intrathymic delivery of donor B cells plus depleting antiCD4 mAb can induce indefinite prolongation of the cardiac grafts but not pancreatic islet or skin grafts. REFERENCES 1. Niimi M, et al: Transplant Immunol 6:177, 1998 2. Niimi M, et al: Transplantation 64:1330, 1997 3. Turvey SE, et al: Transplantation 68:30, 1999 From Nuffield Department of Surgery, University of Oxford, Oxford, UK (K.J.W.), 1st Department of Surgery, Teikyo University, Tokyo, Japan (M.N., Y.I., N.S., T.S., H.T., S.K.); Department of Surgery, Keio University, Tokyo, Japan (K.M.); and 1st Department of Surgery, Yamaguchi University, Yamaguchi, Japan (K.H., K.E.). Address reprint requests to M. Niimi, 1st Department of Surgery, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan.

© 2000 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010 Transplantation Proceedings, 32, 2020 (2000)