Carly J. Callender a,*, Marcelo Fernandez-Vina b, Mary S. Leffell a, Andrea A. Zachary a
a The Johns Hopkins Immunogenetics Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
b Stanford University School of Medicine, Department of Pathology/Blood Center, Palo Alto, CA 94304, USA
Received 14 July 2011
Accepted 7 November 2011
Available online 23 November 2011
Keywords: HLA-DP DP CREG
Clinical studies have demonstrated that HLA-DP-specific antibodies can be detrimental to a transplanted kidney. The number of patients affected is proportional to the frequency of DP antibodies.Wedetermined the frequency of HLA-DP-specific antibodies en toto and in the absence of cross-reactive DR antibodies. Of 650 waitlisted renal patients, 271 (42%) were reactive with HLA-DP antigens in solid-phase immunoassays. Of these 271 sera, 58 (21%) were negative for reactivity with cross-reactive DR antigens, and 16 (5.9%) had no class II antibody other than DP. Eliminating sera containing DR cross-reactive antibodies reduced the frequency but not the overall strength of DP antibodies. Although most DP antibodies were not expected to yield a positive cytotoxicity crossmatch, 2 DP-specific antibodies yielded cytotoxic crossmatch tests with titers of 512. The occurrence of HLA-DP-specific antibody differed significantly between previously transplanted (62%) and nontransplanted (38%) patients, but no difference was observed among patients categorized by race or sex. One serum demonstrated strong cross-reactivity between DP and DRB1*01:03 in the absence of DR1 or DR11 reactivity. Sequence alignments were performed and a possible new cross-reactivity between DRB1*01:03 and DP2, DP9, DP10, DP13, DP16, and DP17 was defined. Two additional sera confirmed this cross-reactivity.
2012 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.