Western Blot for IgG and LILRB1

The western blot was performed using standards protocols as previously described^{3 (link)}. Briefly, B cell supernatants or recombinant antibody constructs were diluted in H₂O, 4x sample loading buffer and 10x sample reducing agent (Life Technologies) were loaded onto precast gels with a 4-12% acrylamide gradient (Invitrogen). The proteins were transferred to PVDF membranes followed by blocking with 5% milk in TBS buffer. The membrane was incubated with primary and secondary antibodies diluted in 2% milk TBS buffer for 1h at room temperature. After washing with the TBS-tween buffer, the membranes were developed using a chemiluminescent substrate (Thermo Scientific). The primary antibodies for detecting IgG or LILRB1 were goat anti-human IgG (SouthernBiotech, 2040-05) used at 2 μg/ml or goat anti-human LILRB1 used at 5 μg/ml (R&D, AF2017). The secondary antibody for both western analyses was rabbit anti-goat HRP used at 0.2 μg/ml (Invitrogen, Catalog 65-6120).