Development of Immunocapture-LC/MS Assay for Simultaneous ADA Isotyping and Semiquantitation

Table 6

LC/MS peak area ratio responses and calculated ADA isotope/subclass levels in PEA positive human plasma with mouse Ab as ADA capture reagent (numbers in bold italic are above respective cut-points). Plasma samples were spiked with addition of excessive drug (+drug) or without (−drug) addition of excessive drug.

Lot #	IgG1		IgG2		IgG3		IgG4		IgE		IgM		IgA
	−drug	+drug	−drug	+drug	−drug	+drug	−drug	+drug	−drug	+drug	−drug	+drug	−drug	+drug
1	0.0369	0.1860	0.0077	0.0106	—	—	0.0668	0.0823	—	—	0.0159	0.0094	0.0194	0.0411
2	0.0145	0.0563	0.0072	0.0066	—	—	0.0584	0.0458	—	—	0.0316	0.0340	0.0033	0.0113
3	0.0354	0.2330	0.0074	—	—	—	0.0634	0.0594	—	—	0.0268	0.0098	0.0405	0.0483
4	0.0212	0.0715	0.0240	0.0314	—	—	0.0484	0.0369	—	—	0.0045	0.0190	0.1380	0.2300
5	0.0350	0.0381	—	0.0059	—	—	0.0182	0.0150	—	—	0.0053	0.0118	0.0325	0.0692
6	0.0731	0.1800	0.0122	0.0237	—	—	0.0325	0.0544	—	—	0.0575	0.0310	0.1810	0.1900
7	0.0231	0.0343	0.0469	0.0739	—	—	0.0685	0.0768	—	—	0.0234	0.0321	0.0339	0.0476
8	0.0463	0.0474	0.0086	0.0045	—	0.0915	0.0572	0.0528	—	—	0.0089	0.0394	0.0142	0.0329
9	0.0396	0.1160	0.0011	0.0026	—	—	0.0661	0.0404	—	—	0.0094	0.0125	0.0437	0.0681
10	0.0188	0.1200	0.0020	0.0039	—	—	0.0151	0.0225	—	—	0.0275	0.0329	0.0029	0.0208
11	0.0974	0.5690	0.0094	0.0075	—	—	0.0294	0.0305	—	—	0.2570	0.2850	0.1040	0.1050
Cut-point (95%)	0.0680		0.0466		0.0000		0.1168		0.0100		0.0775		0.0617

—: no LC/MS response was detected.