The Anti-IL‑4 antibody has been designed for intracellular staining of IL‑4–producing cells. Cells can be stimulated for IL‑4–production, e.g., by polyclonal stimulation with mitogens. For induction of IL‑4 production by antigen-specific T cells, cells are restimulated with respective antigen. IL‑4 can be accumulated in the cells by addition of secretion inhibitors like brefeldin A. After fixation and permeabilization of the cell sample, IL‑4–producing cells can be stained intracellularly with the Anti-IL‑4 antibody. Staining of surface markers allows simultaneous flow cytometric analysis of subsets and activation status of the IL‑4–producing cells. Magnetically enriched cells can be stained intracellularly for IL‑4 production directly on the MACS®
Column. This procedure ensures higher sensitivity of detection and minimizes loss of cells during washing procedures for cytokine analysis of rare cells, e.g., CD4+
T cells in HIV patients, or other cell sources than peripheral blood mononuclear cells (PBMCs), e.g., bronchoalveolar lavages, or synovial fluids.