C1Q Assay Results in Complement-Dependent Cytotoxicity Crossmatch Negative Renal Transplant Candidates with Donor-Specific Antibodies: High Specificity but Low Sensitivity When Predicting Flow Crossmatch

الملخص EN

The aim of the present study was to describe the association of positive flow cross match (FXM) and C1q-SAB.

Methods.

In this observational, cross-sectional, and comparative study, patients included had negative AHG-CDC-XM and donor specific antibodies (DSA) and were tested with FXM.

All pretransplant sera were tested with C1q-SAB assay.

Results.

A total of 50 donor/recipient evaluations were conducted; half of them had at least one C1q+ Ab ( n = 26 , 52%).

Ten patients (20.0%) had DSA C1q+ Ab.

Twenty-five (50%) FXMs were positive.

Factors associated with a positive FXM were the presence of C1q+ Ab (DSA C1q+ Ab: OR 27, 2.80–259.56, P = 0 .

004 , and no DSA C1q+ Ab: OR 5, 1.27–19.68, P = 0 .

021 ) and the DSA LABScreen-SAB MFI (OR 1.26, 95% CI 1.06–1.49, P = 0 .

007 ).

The cutoff point of immunodominant LABScreen SAB DSA-MFI with the greatest sensitivity and specificity to predict FXM was 2,300 (sensitivity: 72% and specificity: 75%).

For FXM prediction, DSA C1q+ Ab was the most specific (95.8%, 85–100) and the combination of DSA-MFI > 2,300 and C1q+ Ab was the most sensitive (92.0%, 79.3–100).

Conclusions.

C1q+ Ab and LABScreen SAB DSA-MFI were significantly associated with FXM.

DSA C1q+ Ab was highly specific but with low sensitivity.