Temperature gradient gel of a dilution experiment. Lane 1, marker (HincII digest of psi 174); lane 2, 100% JM cells; lanes 3 to 6, 10%, 1%, 0.1%, and 0.01% JM cells in PBMC of a healthy volunteer; lane 7, 100% PBMC. Clonality is demonstrated down to 10³ JM cells in 10⁶ polyclonal PBMC (0.1%). a, range of polyclonal smears; b, range of clonal bands.