Table 1.

SELDI-TOF MS protein peaks differentially expressed in paired sera from SJIA before and after therapy

	Before/after conventional therapy		Before/after MRA
Mass (m/z)	P	Patients with visually distinct peaks/total no. of patients	P	Patients with visually distinct peaks/total no. of patients
4504	0.0001		0.005
4758	0.0005		0.0006
5739	0.0001		0.00000008
6441	0.00009		0.0001
6947	0.0005		0.003
9510	0.0007	6/8	0.00001	12/15
9725	0.00006		0.00001
11405	0.00001	8/8	0.000000003	14/15
11520	0.000007	8/8	0.000000001	14/15
11641	0.000005	8/8	0.0000000001	14/15
11718	0.0004		0.00002
11880	0.0002		0.0000006
12703	0.0006	7/8	0.04	6/15
20816	0.0002	7/8	0.01	9/15
22389	0.0002		0.00005
23627	0.0002		0.09
28734	0.0002		0.00006
33457	0.00001	6/8	0.00001	11/15
66637	0.0001	7/8	0.000009	11/15
74886	0.0006		0.00003
75622	0.0009		0.0001
76319	0.0008		0.00002
79216	0.0007		0.000003

Differences between mass spectra of sera before and after conventional therapy. Sera from eight patients with SJIA who responded to conventional therapy were analyzed before and after therapy by SELDI-TOF MS using Ciphergen IMAC-3 copper chips. All samples were run in duplicate. Only variables with nonparametric P values of <0.001 are given. Of 282 spectral peaks identified, the 23 listed here had mean signal intensities significantly different (P < 0.001) before and after response to treatment. Proteins are listed according to mass/charge ratio. Visually distinct peaks (in bold type) refers to peaks that were clearly different between paired samples from before and after treatment upon visual inspection of the profiles, as shown in Fig. 1. The numbers of patients in whom these peaks were visually distinct are shown in columns 3 and 5. These peaks represent potential biomarkers of active disease. IMAC-3, immobilized metal affinity capture; MRA, humanized anti-IL-6 receptor monoclonal antibody; SELDI-TOF MS, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry; SJIA, systemic juvenile idiopathic arthritis.