This commonly results in direct sensitization against the partner, potentially making

him an unsuitable donor. HAR may also occur in blood group incompatible transplantation without desensitization. Preformed antibodies cause rejection by binding to HLA antigens expressed on the endothelium of vessels in the transplanted kidney, resulting in activation of the complement cascade with resultant thrombosis and infarction of the graft (reviewed in2). HAR can occur immediately upon reperfusion of MK-8669 clinical trial the donor kidney. This catastrophic outcome necessitates the immediate removal of the graft. Clearly avoiding HAR is desirable and crossmatching helps predict and hence prevent this.3 In brief, a crossmatch involves placing recipient serum (potentially containing donor-specific anti-HLA antibodies) onto donor lymphocytes (containing HLA antigens). A cytotoxic reaction (deemed ‘positive’) suggests the presence of preformed DSAbs. A more detailed description is provided later in this manuscript. A 44-year-old woman with end-stage renal failure secondary to reflux nephropathy is interested in a renal transplant and her husband has offered to be a donor. They are of the same blood group but are unmatched on tissue typing (0/6 HLA matches at the HLA-A, -B and -DR loci). They have a complement-dependent cytotoxicity (CDC) crossmatch performed as part of their initial assessment, which shows a positive result for both the T- and B-cell crossmatch (Table 1). Is it safe

to second proceed? It is not safe to proceed in light of these crossmatch results but clarification steps are needed to better

understand R788 research buy the reason for the positive results. This could be a falsely positive result (technical issue) or there may be autoantibodies (against lymphocyte antigens) present in the recipient serum. Autoantibodies are generally IgM rather than IgG antibodies. To establish if autoantibodies are responsible for the result an auto-crossmatch should be performed. In this assay, recipient serum is crossmatched against recipient (rather than donor) lymphocytes. Second, the original crossmatch should be repeated with the addition of the agent Dithiothreitol (DTT). DTT reduces the disulfide bonds in IgM thereby preventing IgM antibodies from generating a positive result. IgM antibodies are generally regarded as having no pathological significance in transplantation.4–7 If a repeat crossmatch with DTT is negative then it may be safe to proceed with the transplant. An auto-crossmatch adds weight to this analysis by determining if the recipients are reacting against their own T or B cells in a similar way (Table 2). These results suggest that the reaction of the recipient to the donor is on the basis of autoantibodies. This means that the transplant could proceed using this pairing; however, before most live donor transplants and indeed cadaveric transplants more information is routinely available that aids in forming a more complete assessment of immunologic risk.