sIgM staining
DT40 B cells (2x106 cells per point) were resuspended in 200mul buffer (RPMI 1640 media, 1% foetal calf serum) containing anti-chicken M1 monoclonal antibody conjugated to FITC for 20min on ice. The cells were washed twice and fluorescent intensity was analysed by flow cytometry. 
All results shown are representative of at two to four independent experiments unless otherwise indicated. 
