SELDI-TOF analysis before and after fractionation using IgY12 spin columns. SELDI-TOF spectrum (between 3,000 and 15,000 m/z) of the original unfractionated serum (panel a), of the unbound (depleted) (panel b) and Y12 bound (panel c) protein fractions. Stars indicated peaks present only in one of the fraction. Panel d: hierarchical clustering using the peaks detected in the a to c panel (in duplicates) using the ProteinChip Software (Ciphergen Biosystems). Numbers on the top represent the m/z values of the peaks. Colors are related to relative distribution between the fractions; green: low level, red: high level, black average level. Triangles and stars indicated peaks that appeared specific of the unbound fraction or present in both bound and original fractions, respectively. Panel e: SEDLI-TOF spectra of pure IL-8 revealing a single peak with an apparent m/z value of 8560. Serum spiked with 0.1 ng/μL of IL-8 was analysed before (panel f) or after (panel g) immunodepletion. A peak (triangle) aligned to that of the IL-8 was only readily detected after depletion in the unbound fraction. The additional peak in this fraction (triangle) corresponded, as in panel c, to an additional serum peak detected only after depletion.