Every transplant team wants a definitive answer for the compatibility of a potential recipient with a specific donor. The Mean Equivalent Standard Fluorescence is a level of fluorescence (MESF) that a flow cytometer measures based on the amount of bound IgG antibody on the donor cell. The cutoff MESF determination (positive = black/ negative=white) is developed for each lab based on their programs priorities. The reality is there are many shades of grey using one predetermined cut off for T and B cells. Our program uses 1500 MESF for T cells and 2500 MESF for B cells. The question is; would a crossmatch resulting in 2100 for T cells and 3100 for B cells be contraindicative of compatibility? We have studied 131 crossmatches from sensitized potential renal transplant recipients and deceased donors. We use a current and historic (<six months) patient sera for T and B cell flow crossmatches. There were 22 positive crossmatches studied out of 131 performed from 7-1-2011 to 6-30-2012. All of the potential renal transplant recipients demonstrated anti-HLA antibodies (N=131). None had demonstrable anti-HLA antibodies to the donor antigens at the time of crossmatch. We use pronase treated cells in a T and B cell flow crossmatch procedure with Mean Equivalent Standard Fluorescence (MESF) as a read out. Several crossmatches (n=13), (59 %) had IgM interference that was reduced with Dithithreatol (DTT). The untreated sera were positive without DTT treatment and became negative after DTT treatment for both T and B cells. Flu vaccination has been shown to increase anti-HLA antibody activity and may result in a B cell non-specific activation or reactivation. In conclusion: The reduction of IgM in potential recipient sera with DTT, in our laboratory, has allowed a greater number of sensitized patients to be transplanted. 2) An auto crossmatch (donor cells and donor sera) is employed to determine background fluorescence i.e. autoantibody status, and 3) black= positive or white= negative in some deceased donor crossmatches is difficult to determine. Each cases crossmatch result close or ∼500 MESF above the cutoff (grey area) must be evaluated with the patient necessity for that transplant in mind to determine, if the transplant should be performed.
To cite this abstract in AMA style:Cirocco R, Mendiolina J, Biondi L, Moritz M. Flow Crossmatching for Renal Transplantation in the Virtual Crossmatch Era: Fifty Shades of Grey [abstract]. Am J Transplant. 2013; 13 (suppl 5). https://atcmeetingabstracts.com/abstract/flow-crossmatching-for-renal-transplantation-in-the-virtual-crossmatch-era-fifty-shades-of-grey/. Accessed October 28, 2020.
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