Haynes ATC 2010.05 | Immune Tolerance Network

Abstract Title:

Donor Specific Regulation and B Cell Tolerance Signature in Renal Transplant Recipients.

Author List:

Haynes LD, Jankowska-Gan E, Seyfert-Margolis VL, Newell KA, Turka LA, Asare A, Bourcier KD, Burlingham WJ.

Affiliations:

University of Wisconsin, Madison, WI Immune Tolerance Network, Bethesda, MD Emory University, Atlanta, GA University of Pennsylvania, Philadelphia, PA

Understanding and identifying differences between transplant recipients who maintain good allograft function despite minimal or no immunosuppression (IS) and those that require full IS to avoid rejection has been elusive. The purpose of this study is to compare donor specific regulation (DSR) with a recently defined B cell signature of tolerance in a group of renal transplant (RTx) recipients.

Methods: RTx patients (n=44) included those on standard IS (n=16), prednisone monotherapy (n=6), no IS (TOL; n=12), identical twin (n=2), or chronic rejection (n=8). Blood was monitored by flow cytometry for total B cells (CD19+) and nave B cells (CD19+, CD27-, IgM+, IgD+), and by RT-qPCR of mRNA (Sequenom, San Diego, CA). The B cell tolerance signature includes elevated total and nave B cells in blood and elevated expression of 2 B cell associated genes. DSR was monitored by trans-vivo delayed type hypersensitivity (tvDTH) bystander suppression assay and defined as 50% inhibition of recall response when donor Ag was present. Wilcoxon Rank Sums analysis was performed.

Results: When all patients were divided by DSR phenotype, we found that significantly more of the DSR+ subjects also had a B cell tolerance signature with high circulating nave and total B cells, and high mRNA gene expression of one of the tolerant B cell genes (Table 1). Within the TOL group, the 3 recipients who were NOT DSR+ had significantly lower nave B cell numbers as compared with the 9 DSR+ pts (58 vs 218, p=0.05). Interestingly, both recipients of RTx from an identical twin lacked DSR (0% inhibition) and had normal/low levels of circulating nave & total B cells (<100 K cells/).

Comparison of B cell Signature with DSR
Group (n)	Naive B cell #	Total B cell #	Gene 1 x 10⁶ copies	Gene 2 x 10⁶ copies	% Inh of tvDTH
DSR+	137 ( 32)	216 ( 49)	1.93 ( 0.5)	1.44 ( 0.4)	59%
DSR-	60 ( 28)	118 ( 43)	0.93 ( 0.6)	0.53 ( 0.4)	14%
p value	0.02	0.03	0.17	0.03	<0.0001

Conclusions: Renal transplant recipients with donor specific regulation of recall T cell responses in the human-to-mouse tvDTH assay also display a B cell tolerance signature.

Abstract Number:

1578

Meeting Name:

2010 American Transplant Congress

Meeting Place:

San Diego, CA

Meeting Dates:

May 1-5

Publication/Meeting Year:

2010

Study Code:

ITN Registry of Tolerant Kidney Transplant Recipients