Detection by Flow Cytometry of Anti-DNA Autoantibodies and Circulating DNA Immune Complexes in Lupus Erythematosus

Table 1

Clinical sensitivity and specificity of anti-dsDNA detection tests in a cross-sectional analyses. 63 serum samples of SLE are classified according to the results observed on the usCLIFT.

	Nb of positive sera (%)
	usCLIFT positive	EliA™-dsDNA		FCM test
				IC-ctDNA^+	IC-eDNA^
Control
	1 (1.1%)	22 (25%)	4 (4.6%)	5 (5.7%)	2 (2.3%)
SLE^&
	46 (73%)	48 (76%)	30 (48%)	35 (56%)	21 (33%)
usCLIFT-
		8 (47%)	1 (5.9%)	3 (18%)	4 (24%)
usCLIFT+
		40 (87%)	29 (63%)	32 (70%)	17 (37%)
Sensitivity^§	0.73	0.76	0.48	0.56	0.33
Specificity	0.99	0.75	0.95	0.94	0.98

The threshold of positivity according to the manufacturer is 15 IU/ml; however, according to the SLICC criteria and published results, the threshold in ELISA for the diagnosis of SLE should be twice the threshold of positivity [2, 35].⁺IC-ctDNA, , for the concordance with usCLIFT or EliA™-dsDNA > 30 IU and with EliA™-dsDNA > 15 IU. ^No statistically significant relationship between the presence of circulating IC-eDNA and the results of anti-DNA detection by usCLIFT or EliA™-dsDNA. ^&The results of all tests including IC-eDNA are statistically significant between SLE sera and control samples, . ^§In order not to introduce any difference in the sensitivity and the specificity due to the labeling of the different antibody isotypes, the same FITC-conjugated antiserum to human immunoglobulins (IgG, IgA, IgM) was used in the FCM test and in the usCLIFT. The sensitivity of the usCLIFT was higher than the FCM test and EliA™-dsDNA > 30 IU, .