Two color flow cytometric analysis of TNF expression by stimulated mouse splenocytes. Mouse splenic leucocytes were stimulated for 5 hours with Phorbol 12-Myristate 13-Acetate (PMA; Sigma P-8139; 50 ng/ml) and Ionomycin (Sigma I-0634; 1 μg/ml) in the presence of BD GolgiStop™ Protein Transport Inhibitor (containing Monensin) (Cat. No. 554724). The cells were harvested and washed with BD Pharmingen™ Stain Buffer (FBS) (Cat. No. 554656) and fixed and permeabilized with BD Cytofix/Cytoperm™ Fixation and Permeabilization Solution (Cat. No. 554722). The cells were then washed and stained in BD Perm/Wash™ Buffer (Cat. No. 554723) with APC Rat Anti-Mouse CD4 antibody (Cat. No. 553051/561091) and either BD Horizon™ BV421 Rat IgG1, κ Isotype Control (Cat. No. 562868; Left Panel) or BD Horizon™ BV421 Rat Anti-Mouse TNF antibody (Cat. No. 563387; Right Panel) by using BD Biosciences Intracellular Cytokine Staining protocol. Flow cytometric dot plots showing correlated expression of TNF (or Ig Isotype control staining) versus CD4 were derived from gated events with the forward and side light-scatter characteristics of intact stimulated leucocytes. Flow cytometric analysis was performed using a BD LSRFortessa™ Cell Analyzer System.