Others contend that flow click here crossmatching adds important information on the strength of donor-specific antibody reactivity and should be considered in the context of donor-specific antibody results and CDC crossmatching to help develop an overall opinion on the likelihood of immune complications. The area remains controversial and no clear recommendation can be made at this
time. A 65-year-old man who has end-stage renal failure as a result of ANCA vasculitis has been on dialysis for 4 months. He has had three blood transfusions in the past. His wife has been assessed as a possible renal donor for him. Their immune compatibility is defined below. Is it safe to proceed with transplantation? (Table 5) Proceeding with transplantation in the setting of a negative CDC and flow crossmatch is generally considered as low risk and is reasonable without a desensitization protocol. The issue here is the HLA A23 DSAb detected by Luminex antigen-coated beads (Luminex). Despite the lack of reaction on crossmatching the presence of a DSAb may have prognostic significance for the transplanted kidney and should be further considered before proceeding.23,24 Many transplant units screen all patients on their cadaveric waiting list for anti-HLA antibodies using Luminex and if positive the specificity of the anti-HLA Abs are defined. This means that the transplant clinician can perform a ‘virtual crossmatch’ at the time of a cadaveric renal
transplant Dabrafenib offer as well as in the live donor transplant setting. While outcomes for DSAb positive transplants are inferior to DSAb negative transplants a decision to proceed with a DSAb-positive, CDC crossmatch-negative transplant, in a highly sensitized recipient, may in some cases be in the patient’s best interests. Virtual crossmatching refers to the comparison of the anti-HLA antibodies of the recipient, as defined by Luminex, with the HLA of the donor.25 If there is a DSAb present this would represent a positive virtual crossmatch. Antibodies are defined against HLA class I and II antigens. Synthetic
microspheres (beads) coated with HLA antigens are commercially available for this testing. Beads may be coated with multiple HLA antigens for Glycogen branching enzyme screening purposes or a single HLA antigen for defining specificity of antibodies more precisely (see Fig. 3). For the virtual crossmatch, multiple beads each coated with a single HLA antigen are mixed with recipient serum. Anti-HLA antibodies present bind to the beads and are detected by an isotype-specific (e.g. IgG) detection antibody via flow cytometry. Unique fluorochromes within the beads mark the HLA antigen specificity of each bead (reviewed in26). This technique is as sensitive as flow crossmatching and provides the specificity of the antibody.27 It has long been established that the presence of antibodies that react with human leucocytes portend worse long-term graft survival.