Table 1.

Results of the technical comparison of indirect immunofluorescence (IIF), immunoblot and ELISA for the detection of anti-polymyositis/scleroderma (anti-PM/Scl) antibodies

Sample number	IIF		Immunoblot			ELISA
	Titer	Pattern	PM/Scl-75	PM/Scl-100	Other	PM/Scl-100	PM1-α
1	1:10000	FG, N	++	+++		15.3	17.7
2	1:1000	FG, N	+	+		2.9	7.6
3	1:3200	FG, N	++	++		14.4	29.2
	1:320	AMA
4	1:320	FG, N	-	+		1.1	4.7
5	1:1000	FG, N	+	+		2.2	12.1
6	1:3200	FG, N	-	-		0.6	2.3
7	1:1000	FG, N	++	+++		5.2	13.3
8	1:1000	FG, N	+	+		2.3	12.7
9	1:3200	FG, N	+	+++	P38	15.5	36.1
10	-		-	+		1.7	4.0
11	1:1000	FG, N	-	++		19.2	2.4
12	1:1000	FG, N	++	+		1.2	3.2
13	1:3200	FG, N	+++	+++	Ku86, Jo-1	6.5	10.6
14	1:3200	FG, N	-	++		2.1	5.9
15	1:3200	FG, N	++	+++		11.4	22.5
16	1:1000	FG, N	-	+		3.6	8.5
17	1:1000	FG, N	+	++		3.2	15.0
18	1:3200	FG, N	++	++		6.1	11.8
19	n.d.	n.d.	-	++		7.1	19.4
20	1:320	N	-	+		2.1	5.6
21	n.d.	n.d.	+++	++		4.1	12.8
22	1:10000	FG	-	+	P38	0.7	1.5
	1:10000	SPA
23	1:1000	N	n.d.	n.d.		0.5	2.7
24	n.d.	n.d.	++	+++		18.2	34.7
25	1:10000	N	n.d.	n.d.	P38	0.5	2.0
	1:1000	Rib
26	1:1000	N	n.d.	n.d.		1.9	8.4
27	n.d.	n.d.	+	++		5.9	19.4
28	n.d.	n.d.	++	+++		20.9	37.3
29	1:1000	Hom	n.d.	n.d.	Ku86, Cen, M2	0.6	0.8
	1:100	N*
30	1:1000	N	-	+		0.6	1.4
31	1:3200	Hom, N	-	-		0.5	2.9
32	1:3200	N	-	-		0.5	1.3
33	1:320	FG, N	+	++		7.2	25.7
Number positive/tested		26/29	17/29	27/29		26/33	32/33

-, negative; +, weak positive; ++, positive; +++, strong positive; n.d., not determined; FG, fine granular; Hom, homogenous; SPA, spindle apparatus; N, nucleoli; AMA, anti-mitochondrial antibodies; Cen, centromere; Rib, ribosomal. * Primate liver.