Catalytic domain of PDC-E2 contains epitopes recognized by antimitochondrial antibodies in primary biliary cirrhosis

Table 2 Reactivity and incidence of IgG-antibodies to 33 PDC-E2 peptides in PBC patients as compared to healthy individuals n (%)

	Peptide No.	Amino acid	PBC patients		Healthy individuals (n = 22)
			Anti-M2+ (n = 95)	AMA-/ANA+ (n = 11)
Outer lipoyl domain (aa 1-80)	1	-2-23	4 (4)	0	1 (5)
	2	16-40	6 (6)	0	2 (9)
	3	33-57	10 (11)	0	2 (9)
	4	50-74	15 (16)	0	0
	5	67-91	26 (27)	0	2 (9)
Hinge	6	84-108	17 (18)	0	3 (14)
	7	101-125	42 (44)1	0	0
Inner lipoyl domain (aa 133-217)	8	118-142	14 (15)	0	1 (5)
	9	135-159	32 (34)	0	0
	10	152-176	28 (29)	0	2 (9)
	11	169-193	11 (12)2	0	2 (9)
	12	186-210	16 (17)	0	1 (5)
	13	203-227	6 (6)	0	3 (14)
Hinge	14	220-244	4 (4)	0	2 (9)
	15	237-261	3 (3)	0	4 (18)
	16	254-278	20 (21)	0	1 (5)
E1/E3-binding site (aa 272-303)	17	271-295	3 (3)	0	1 (5)
	18	288-312	7 (7)	0	1 (5)
Hinge	19	305-329	19 (20)	0	3 (14)
Catalytic site (aa 331-561)	20	322-346	12 (13)	2 (18)	1 (5)
	21	339-363	0	0	1 (5)
	22	356-380	19 (20)	0	1 (5)
	23	373-397	2 (2)	1 (9)	1 (5)
	24	390-414	1 (1)	1 (9)	2 (9)
	25	407-431	53 (56)3	0	4 (18)
	26	424-448	10 (11)	0	1 (5)
	27	441-465	5 (5)	0	2 (9)
	28	458-482	18 (19)	0	0
	29	475-499	55 (58)4	0	1 (5)
	30	492-516	9 (9)	0	0
	31	509-533	17 (18)	0	2 (9)
	32	526-550	2 (2)	0	1 (5)
	33	543-561	11 (12)	0	1 (5)

¹Twelve patients had antibodies only of the IgG-, 28 only of the IgM-, and 30 of the IgG- and IgM-type; in total, 70 (71%) reacted with peptide 7;

²Four patients had antibodies only of the IgG-, 30 only of the IgM-, and 7 of the IgG- and IgM-type; in total, 41 (43%) reacted with peptide 11;

³Seventeen patients had antibodies only of the IgG-, 18 only of the IgM-, and 37 of the IgG- and IgM-type; in total, 72 (76%) reacted with peptide 25;

⁴Two had antibodies only of the IgG-, 16 only of the IgM-, and 53 of the IgG- and IgM-type; in total, 71 (75%) reacted with peptide 29. Similar data as for healthy controls were obtained with sera from patients with auto-immune hepatitis, alcoholic liver disease and collagen disorders. Peptides 3, 10, 11, 25 and 29 are previous and novel immunodominant epitopes. +: Positive; -: Negative.