We have developed a limiting dilution microculture T-cell cloning technique to generate antigen-specific T-cell clones. Cultures contained peripheral blood T-cells, irradiated autologous mononuclear cells (feeders), human AB serum and recombinant IL-2. Colonies were enumerated at 14 days. Under these conditions the cloning efficiency expressed as the frequency of proliferating cells in response to PHA, ranged from 1/1.07 to 1/3.35. In response to tetanus toxoid, the frequency of proliferating cells ranged from 1/415 to 1/5655. Average colony size ranged from 0.7 x 10(5) to 6.2 x 10(5) cells with a mean T-cell recovery of 2.5 x 10(5) cells per microculture. Restimulation of 14-day tetanus toxoid T-cell colonies revealed marked proliferation to PHA and tetanus toxoid but only background responses to PPD. These studies document the development of a rapid, antigen-specific liquid culture T-cell cloning system which is likely to detect T-cell clones that are representative of the original T-cell population. The clones are of sufficient size to be useful in studies of antigen cross-reactivity.