Clonal expansion of human T lymphocytes initiated by dendritic cells

The accessory cell requirements for cloning T cells in the presence of lectin and T cell growth factors were examined with cells from human peripheral blood. We found that dendritic cells were active and perhaps essential. Single CD4⁺ lymphocytes could be cloned with 80% efficiency, and CD8⁺ cells with 50-60% efficiency if 10³ syngeneic or allogeneic dendritic cells were added. Some T cell clones developed even with one dendritic cell. Monocytes or B lymphocytes from blood were at least 100-fold weaker in supporting clonal growth. These findings suggest a specialized feeder cell requirement, namely dendritic cells, for cloning T lymphocytes from single resting precursors.