The CD4+ T Cell Isolation Kit is an indirect magnetic labeling system for the isolation of untouched CD4+ T helper cells from single-cell suspensions of lymphoid organs. Highly pure untouched CD4+ T cells are isolated by depletion of non-CD4+ T cells. Non-CD4+ T cells, i.e. cytotoxic T cells, B cells, NK cells, dendritic cells, macrophages, granulocytes, and erythroid cells, are indirectly magnetically labeled with a cocktail of biotin-conjugated antibodies against CD8a (Ly-2), CD45R (B220), CD49b (DX5), CD11b (Mac-1), and Ter-119, as well as Anti-Biotin MicroBeads. Isolation of CD4+ T cells is achieved by depletion of the magnetically labeled cells. The CD4+ T Cell Isolation Kit includes the Biotin-Antibody Cocktail for labeling of non-CD4+ T cells and Anti-Biotin MicroBeads.