Table 1. Endogenous Peptides and Labeled Standards used for LC-MRM Quantification of Immunoglobulins.
Peptides representative for individual proteins and groups of isoforms are quantified.
| Protein | Average Expression & Reference Range (mg/ml) |
Peptide | IS | Transitions | Median Intra- Assay CV (%) |
Median Inter- Assay CV (%) |
Outliers |
|---|---|---|---|---|---|---|---|
| IgG1 | 5.917 3.19–10.2 |
GPSVFPLAPSSK | 10.2 | y8–y10 | 7.5 | 7.2 | 3 |
| IgG2 | 3.047 1.23–6.63 |
GLPAPIEK | 6.63 | y4–y6 | 6.0 | 5.9 | 2 |
| IgG3 | 0.617 0.16–1.94 |
WYVDGVEVHNAK | 1.94 | y6,y8,y9 | 16 | 18.3 | 12 |
| IgG4 | 0.247 0.03–1.33 |
TTPPVLDSDGSFFLYSR | NS | y8,y10,y12 | -- | -- | -- |
| IgA1 | 1.886 1.36–2.5 |
TPLTATLSK | NS | y5–y7 | -- | -- | -- |
| IgA2 | 0.546 0.28–0.61 |
DASGATFTWTPSSGK* | 0.6 | y7–y10 | 21 | 16 | 5 |
| IgA1-2 | 2.42 1.64–3.11 |
WLQGSQELPR | 3.1 | y6–y8 | 6.8 | 9.6 | 2 |
| IgM | 0.708 0.4–2.3 |
DGFFGNPR | 2.3 | y4–y6 | 11 | 7.6 | 1 |
| κ LC | 2.319 1.55–3.08 |
TVAAPSVFIFPPSDEQLK* | 3.0 | y8,y9,y11 | 7.3 | 6.6 | 6 |
| λ LC | 1.549 0.83–2.24 |
AGVETTTPSK | 2.24 | y5–y7 | 19 | 9.0 | 16 |
| IgD | 0.013910 0.001–0.024 |
EPAAQAPVK | 0.50 | y5–y7 | 0.52 | -- | 0 |
| IgE | 0.000111 0–0.002 |
GSGFFVFSR* | 0.50 | y5–y7 | 6.7 | -- | 0 |
| Albumin | 3511 30–40 |
LVNEVTEFAK* | 3.5 | y5,y7,y8 | 5.0 | 6.3 | 0 |
Standard peptides were synthesized with either isotope-labeled amino acids or with a structural analog created by single conservative amino acid replacement (as noted by *) that differs only by a methylene group in the side chain of the underlined residue. The limit of detection based on internal standards is also shown along with other monitored peptides that do not have quantitative assays developed. Eleven additional peptides are monitored to improve confidence in quantification by evaluation of consistency, but SIS peptides have not been synthesized. Reference ranges provided by ARUP Laboratories.