Comparison of CD4 mRNA content in neutrophils and PBMCs. Levels of CD4 mRNA in purified PBMCs and neutrophils from uninfected control 1 (displaying CD4⁺ neutrophils) and control 2 (displaying CD4^–neutrophils) were determined by real-time PCR assay. The amount of CD4 mRNA in autologous PBMCs is used as an internal calibrator in each donor. Purified PBMCs and neutrophils from control 1 prepared in an independent experiment yielded similar results in terms of CD4 mRNA content (not shown).