Figure 1.

Monitoring individual plasma IgG1 profiles

(A) Longitudinal analysis of the IgG1 repertoire from sepsis patient plasma obtained at four time points, reveals its simplicity and clonal dynamics: some clones are fairly constant (green), some disappear (blue), whereas others appear over time (red).

(B) The experimental approach taken involves IgG capturing from 10–100 μL of serum, followed by the specific enzymatic digestion of the IgG1 molecules in their hinge region, generating two identical Fab portions. All generated Fabs are collected and subsequently subjected to LC-MS analysis. The clonal repertoire is profiled, whereby each identified clone is characterized by its unique mass and retention time. A single post-sepsis clone from one of the patients (F59) was selected for de novo sequencing, combining protein- and peptide-centric mass-spectrometry-based sequencing. The extracted full sequence of the plasma IgG1 was validated by analyzing, in a similar manner, a recombinant IgG1 analog of the plasma clone.