Autoreactive CD4⁺ helper T cells specific for a range of nucleoprotein-derived autoantigens are an important feature of systemic lupus erythematosus, driving B cell differentiation and autoantibody production and contributing to the inflammatory lesions caused by immune complex deposition. Several peptide epitopes from nucleoprotein antigens have been identified and offer a means selectively to manipulate T cell responses by skewing toward a profile of cytokines that is less pro-inflammatory. Antigen-specific T cell lines and clones can be useful in the study of helper T cell subsets because their life span is prolonged and many individual cells can be generated, allowing particular phenotypes to be studied in detail. Magnetic beads offer a robust and convenient method for the isolation, polarization, and expansion of T cells, which can be adapted for a broad range of applications.