title: B cell repertoires in HLA-sensitized kidney transplant candidates undergoing desensitization therapy.
abstract: Kidney transplantation is the most effective treatment for end-stage renal disease. Sensitization refers to pre-existing antibodies against human leukocyte antigen (HLA) protein and remains a major barrier to successful transplantation. Despite implementation of desensitization strategies, many candidates fail to respond. Our objective was to determine whether measuring B cell repertoires could differentiate candidates that respond to desensitization therapy.
  
  
  
  We developed an assay based on high-throughput DNA sequencing of the variable domain of the heavy chain of immunoglobulin genes to measure changes in B cell repertoires in 19 highly HLA-sensitized kidney transplant candidates undergoing desensitization and 7 controls with low to moderate HLA sensitization levels. Responders to desensitization had a decrease of 5% points or greater in cumulated calculated panel reactive antibody (cPRA) levels, and non-responders had no decrease in cPRA.
  
  
  
  Dominant B cell clones were not observed in highly sensitized candidates, suggesting that the B cells responsible for sensitization are either not present in peripheral blood or present at comparable levels to other circulating B cells. Candidates that responded to desensitization therapy had pre-treatment repertoires composed of a larger fraction of class-switched (IgG and IgA) isotypes compared to non-responding candidates. After B cell depleting therapy, the proportion of switched isotypes increased and the mutation frequencies of the remaining non-switched isotypes (IgM and IgD) increased in both responders and non-responders, perhaps representing a shift in the repertoire towards memory B cells or plasmablasts. Conversely, after transplantation, non-switched isotypes with fewer mutations increased, suggesting a shift in the repertoire towards naïve B cells.
  
  
  
  Relative abundance of different B cell isotypes is strongly perturbed by desensitization therapy and transplantation, potentially reflecting changes in the relative abundance of memory and naïve B cell compartments. Candidates that responded to therapy experienced similar changes to those that did not respond. Further studies are required to understand differences between these two groups of highly sensitized kidney transplant candidates.
authors.affiliation: CareDx, 3260 Bayshore Blvd, Brisbane, CA, 94005, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Beausang
authors.affiliation: Immumetrix, LLC, 3183 Porter Drive, Palo Alto, CA, 94304, USA.
authors.forename: H Christina
authors.initials: HC
authors.lastname: Fan
authors.affiliation: CareDx, 3260 Bayshore Blvd, Brisbane, CA, 94005, USA.
authors.forename: Rene
authors.initials: R
authors.lastname: Sit
authors.affiliation: Immumetrix, LLC, 3183 Porter Drive, Palo Alto, CA, 94304, USA.
authors.forename: Maria U
authors.initials: MU
authors.lastname: Hutchins
authors.affiliation: Immumetrix, LLC, 3183 Porter Drive, Palo Alto, CA, 94304, USA.
authors.forename: Kshama
authors.initials: K
authors.lastname: Jirage
authors.affiliation: Immumetrix, LLC, 3183 Porter Drive, Palo Alto, CA, 94304, USA.
authors.forename: Rachael
authors.initials: R
authors.lastname: Curtis
authors.affiliation: Immumetrix, LLC, 3183 Porter Drive, Palo Alto, CA, 94304, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Hutchins
authors.affiliation: Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA, 94305, USA.|Howard Hughes Medical Institute, Stanford, CA, USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Quake
authors.affiliation: Department of Medicine, Stanford University School of Medicine, 750 Welch Road, Palo Alto, CA, 94304, USA. jyabu@berkeley.edu.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Yabu
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology*; D003888:Desensitization, Immunologic; D005260:Female; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D000069283:Rituximab / Q000627:therapeutic use
chemical_list: D006680:HLA Antigens; D016756:Immunoglobulins, Intravenous; D000069283:Rituximab
keywords: B cells; DNA sequencing; Desensitization; HLA sensitization; Immune repertoire; Kidney transplantation