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

Table 1

Factors associated with a positive FXM. DSA determinations are expressed according to the LABScreen SAB results. MM = mismatches.

	All samples ()	Positive FXM ()	Negative FXM ()	value
Recipient age, m (SD)	35.0 ± 12.7	33.8 ± 11.2	36.2 ± 14.1	0.510
Recipient male gender, (%)	23 (46.0)	9 (36.0)	14 (56.0)	0.156
Donor age, m (SD)	42.2 ± 11.9	43.7 ± 10.6	40.7 ± 13.1	0.385
Donor male gender, (%)	21 (42.0)	12 (48.0)	9 (36.0)	0.390
Previous transplant, (%)	18 (38.3)	12 (50.0)	6 (26.1)	0.092
HLA MM, med (IQR)	4 (4–6)	4 (3–6)	4 (4–6)	0.889
HLA MM DR/DQ, med (IQR)	2 (1-2)	2 (2-2)	2 (1-2)	0.495
% PRA class I, med (min–max)	15 (0–90)	14.0 (2–90)	16 (0–60)	0.259
% PRA class II, med (min–max)	10 (4–24)	13 (1–89)	9 (0–100)	0.466
Class I DSA, (%)	29 (58.0)	14 (56.0)	15 (60.0)	0.774
Class II DSA, (%)	35 (70.0)	18 (72.0)	17 (68.0)	0.758
HLA antibodies analyzed by LABScreen SAB
of DSA, m (min–max)	1.72 (1–6)	1.84 (1–6)	1.6 (1–4)	0.769
MFI DSA, med (IQR)	2,138 (1,160–7,147)	5,166 (1,457–12,829)	1,457 (1,113–2,293)	0.001
of all HLA-Ab, med (IQR)	12 (6–28)	12 (10–26)	8 (4–28)	0.164
MFI all HLA-Ab, med (IQR)	10,128 (3,813–15,407)	13,312 (5,681–18,666)	3,937 (2,192–13,312)	0.006
HLA-A DSA, (%)	16 (32.0)	7 (28.0)	9 (36.0)	0.544
MFI DSA HLA-A, med (IQR)	1,294.5 (763–4,155.5)	4,467 (3,141–11,526)	828 (664–1,113)	0.003
HLA-B DSA, (%)	9 (18.0)	5 (20.0)	4 (16.0)	1.00
MFI DSA HLA-B, med (IQR)	1,427 (759–2,669)	2,669 (1,427–5,670)	838 (706.5–1,190)	0.141
HLA-C DSA, (%)	12 (24.0)	5 (20.0)	7 (28.0)	0.508
MFI DSA HLA-C, med (IQR)	1,866 (843.5–2,739.5)	2,362 (2,303–2,505)	1,247 (612–2,974)	0.329
HLA-DR DSA, (%)	20 (40.0)	9 (36.0)	11 (44.0)	0.564
MFI DSA HLA-DR, med (IQR)	1,752.5 (1,177.5–3,986)	5,145 (1,457–8,651)	1,515 (1,127–2,216)	0.048
HLA-DQ DSA, (%)	21 (42.0)	13 (52.0)	7 (32.0)	0.152
MFI DSA HLA-DQ, med (IQR)	7,147 (1,247–14,710)	12,829 (1,578–17,976)	1,615 (908.5–5,710)	0.042
HLA antibodies by C1q assay
All C1q+ Ab, (%)	26 (53.06)	19 (76.0)	7 (28.0)	0.001
DSA C1q+ Ab, (%)	10 (20.41)	9 (36.0)	1 (4.0)	0.005
Non-DSA C1q+ Ab, (%)	16 (32.65)	10 (40)	6 (24.0)	0.023
HLA-A C1q+ Ab, (%)	6 (12.0)	4 (16.0)	2 (8.0)	0.667
HLA-B C1q+ Ab, (%)	8 (16.0)	6 (24.0)	2 (8.0)	0.247
HLA-C C1q+ Ab, (%)	3 (6.0)	1 (4.0)	2 (8.0)	1.0
HLA-DP C1q+ Ab, (%)	6 (6.0)	3 (12.0)	0	0.235
HLA-DQ C1q+ Ab, (%)	19 (38.0)	16 (64.0)	3 (12.0)	<0.001
HLA-DR C1q+ Ab, (%)	8 (16.0)	7 (28.0)	1 (4.0)	0.049