Non CD3+ T cells are depleted by incubating your sample with the biotin antibody cocktail followed by incubation with magnetic Streptavidin Nanoparticles. The magnetically labeled fraction is retained by the use of a magnetic separator. The untouched CD3+ T cells are collected by decanting the liquid in a clean tube. These are your cells of interest; do not discard the liquid. Some of the downstream applications include functional assays, gene expression, phenotypic characterization, etc.