Growth medium: F17. DNA : 1.33µg/ml. Reagent Amount: 2.66µg/ml. Ratio: 1:2. Complexation medium: F17. Complexation time: 10 min RT. One day prior to transfection. HEK293 cells were passaged at 2.0 - 2.5 X 10^6 cells/ ml. On the day of transfection. cells were pelleted by centrifuging at 400 g for 5 min. and cell pellets were resuspended in fresh FreeStyle F17 medium at a density of 4 X 106 cells/ ml and returned to the incubator. Cultures were harvested six days post transfection by two rounds of centrifugation. each at 2000xg for 5 min

Monoclonal antibodies (mAbs) have recently emerged as one of the most promising classes of biotherapeutics. A potential advantage of B cell-derived mAbs as therapeutic agents is that they have been subjected to natural filtering mechanisms, which may enrich for B cell receptors (BCRs) with favorable biophysical properties. Here, we evaluated 400 human mAbs for polyreactivity, hydrophobicity, and thermal stability using high-throughput screening assays. Overall, mAbs derived from memory B cells and long-lived plasma cells (LLPCs) display reduced levels of polyreactivity, hydrophobicity, and thermal stability compared with naive B cell-derived mAbs. Somatic hypermutation (SHM) is inversely associated with all three biophysical properties, as well as BCR expression levels. Finally, the developability profiles of the human B cell-derived mAbs are comparable with those observed for clinical mAbs, suggesting their high therapeutic potential. The results provide insight into the biophysical consequences of affinity maturation and have implications for therapeutic antibody engineering and development.