Alexa Fluor 561 non-specific staining of B cells in the SJL strain of mice. Splenocytes from BALB/c (left) and SJL (right) strains of mice were stained with Anti-Mouse CD19 Monoclonal Antibody conjugated to FITC and a non-cross-reactive, human-specific monoclonal antibody conjugated to Alexa Fluor 561. These data show that Alexa Fluor 561-conjugated antibodies non-specifically stain B cells in SJL mice (right) and outbred, Swiss Webster mice (data not shown). Non-specific staining has not been observed in BALB/c mice (left) and C57BL/6 mice (data not shown).