Cell viability assay

Cell viability was assessed using the Cell Counting Kit-8 (CCK-8) assay (D-Plus^TM CCK cell viability assay kit; Dong-in Biotech, Seoul, Republic of Korea) to confirm that the concentrations of LPS were not cytotoxic for the B cells. The cells were seeded at a density of 5 × 10⁵ cells/well in a 96-well plate. The medium used was the control, which did not contain LPS, and 5 ng/mL of LPS and 10 ng/mL of LPS were added to the experimental B cell groups. After stimulating the cells for 24 hours, 10 μL of the Cell CCK solution was added, and the cells were incubated in the dark at 37°C for 1 hour. The absorbance at a 450-nm wavelength was determined with a spectrophotometer (Epoch Microplate Spectrophotometer; BioTek Instruments, Winooski, VT, USA).