Weak B Cell Pos.

In the case of an unexpected B cell Positive crossmatch post-transplant, the transplant team needs to be immediately informed. Further testing such as auto-crossmatch may be required if not done already to eliminate auto antibodies. A Luminex SAB test would be carried out in the B cell Pos. sample to determine if the flow reactivity was due to HLA. Post-transplant antibody monitoring would be recommended to identify any potential changes in DSA.

Luminex Does not Correlate with Crossmatch

An investigation is required if the crossmatch results do not correlate with the DSA information as determined by Luminex to understand the clinical implications of the results.

For example, in a situation where the results were historic Luminex DSA Pos. Current Neg, CDC Neg, FXCM T & B Cell Historic and Current Pos. the current FCXM Pos results does not correlate with the current DSA being Negative. In such a situation, the H&I laboratory would want to do FXCM Auto to exclude auto antibodies. They may also want to ask cardiothoracic team about treatments such as Rituximab which could help explain Pos. B Cell FXCM in the absence of DSA. In this particular example, the CDC is IgG Neg so no risk of hyperacute rejection.

If it is confirmed that priming source of this historic HLA antibodies is transfusion related rather than pregnancy or previous transplant and the current FXCM Pos. is due to treatment, the transplant can proceed with HLAi protocol and close post-transplant follow up.