Impact of Rituximab Induction and Living Donation on Immunoregulation and Virus Control in Renal Transplantation - a Prospective Pilot Study
Objective. Blood group incompatible (ABOi) LD renal transplantation represents a recognized
treatment modality in Germany. In this setting, ethical considerations allow for a detailed
study of short- and long-term immunological and virological effects of Rtx induction
therapy, including sequential protocol biopsies. In the proposed project we will perform
analyses on peripheral blood, iliac lymph nodes and protocol biopsies. Protocol biopsies are
routinely obtained 3 and 12 months posttransplant at the Universities of Giessen and
Freiburg. In this prospective, open pilot study, immunological parameters of graft outcome
and control of polyomavirus, EBV and CMV replication will be compared between RTx-treated
ABOi LD renal transplant recipients (n=25-30, group 1) and blood group compatible LD renal
transplant recipients without Rtx induction (n=25-30, group 2) but otherwise comparable
immunosuppressive treatment (MPS and Tacr, switch to Tacr-MR (modified release) within 2
weeks posttransplant; follow-up of 5 years). The same analyses will be done in DD renal
transplant recipients treated with Tacr (switch to Tacr-ME) and MPS (n=25-30, group 3). This
study design allows to analyze the impact of living donation on immunoregulation and virus
control (groups 2 versus 3).
Background. There is growing evidence that humoral mechanisms play a major role in chronic
allograft dysfunction, which was shown to be significantly associated with de-novo formation
of donor-specific HLA antibodies. However, B cells appear to act not only in humoral
responses against the graft but may play a significant role in T-cell mediated antidonor
responses due to their role as effective antigen-presenting cells. This is further suggested
by the fact that Rtx is effective in primarily T-cell mediated diseases such as rheumatoid
arthritis or multiple sclerosis.
Hypothesis/specific aims. We hypothesize that Rtx induction may alter immunoregulation
short- and long-term after renal transplantation with the potential to improve long-term
outcome. Graft protective effects of Rtx induction may be provided by B cell depletion and
the resulting effects on humoral as well as T cell responses, and also by altered responses
after B cell repopulation. Possible negative effects of Rtx on polyomavirus and CMV control
as well as protective effects on EBV replication, de-novo monoclonal gammopathy and
regulation of lymphoma growth factors (IL-6, IL-10) will be analyzed. Furthermore, B cell
subset analysis in peripheral blood and the probably associated impact of Rtx on B cell
depletion in graft draining iliac lymph nodes may enable us to establish an optimized Rtx
dosage and thereby allow successful ABOi renal transplantation without the currently
observed 15% drop outs.
Preliminary results. We have performed clinical studies showing the predictive power of
immune parameters such as regulatory anti-Fab autoantibodies, sCD30, CD4 helper activity,
and CD4 cell IL-4 and IL-10 responses on graft outcome. The long-term effect of Rtx
induction therapy and of living donation on these parameters will be analyzed.
Previously, we found that patients at risk of polyomavirus nephropathy may be recognized
early posttransplant by sequential rt-PCR assessment of polyomavirus replication in urine.
Sequential rt-PCR testing of polyomavirus replication in urine and plasma will be used to
analyze effects of Rtx induction on polyomavirus control.
Proposed methods. Immune parameters will be analyzed mainly pretransplant, 3 months and 1, 2
and 5 years posttransplant. Flow cytometry (including regulatory T cells, B cell subsets,
expression of cytokine receptors, costimulatory and adhesion molecules), mitogen-stimulated
allogeneic cocultures, protein-A plaque assay (B cell responses, CD4 helper activity),
intracellular cytokine analysis of CD4+ and CD8+ T cells, B cells and monocytes, rt-PCR for
virological studies (BK, JC, CMV, EBV) and immunofluorescent staining of iliac lymph nodes
(obtained at time of transplantation) and protocol biopsies will be used. Donor-specific
antibodies will be detected using lymphocytotoxicity, HLA class I and II ELISA and Luminex
assays. Donor-specificity will be confirmed by T- and B-cell crossmatch with donor cells.
Regulatory IgG and IgA anti-Fab autoantibodies, neopterin and sCD30 will be assessed by
Expected results. We expect that Rtx induction will show an impact on immunological
parameters of graft outcome, such as de-novo posttransplant antidonor HLA antibody
formation. This pilot study may allow for improved long-term kidney graft outcome in
recipients with immunologic risk parameters by virtue of patient-tailored immunosuppressive
therapy. In ABOi renal transplantation, this study may prevent the current 15% drop out
rates by allowing an optimized Rtx dosage based on the intended dose response analysis (B
cell subset analysis in blood and graft draining lymph nodes). Furthermore, this study will
allow risk estimation of Rtx administration with respect to CMV and polyomavirus
replication, and may provide clues concerning protection against EBV replication and
posttransplant lymphoproliferative disease. The latter point is of great clinical
importance in patients with an enhanced PTLD risk such as EBV negative recipients of EBV
Allocation: Non-Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment
Impact of Rtx on immune parameters predictive of graft outcome including B cell responses
immune parameters of graft outcome: see "detailed description"
5 years posttransplant
Rolf Weimer, Prof. Dr.
University of Giessen, Department of Internal Medicine
Germany: Federal Institute for Drugs and Medical Devices