Cultivation of T lymphocytes with immobilized anti-CD3 monoclonal antibody and human recombinant interleukin-2 induced a rapid proliferative response. This procedure was applied to expansion culture of peripheral blood lymphocytes obtained from cancer patients for use in adoptive immunotherapy. Peripheral blood mononuclear cells were separated from 20 ml of blood and cultured in anti-CD3 coated flasks with rIL-2 for 6 days, then transferred to a gas-permeable culture bag and culture continued for an additional 8 days with an increasing volume of medium. Cell numbers increased about 2000-fold during this 2-week culture. The final population contained about 30% CD4+ and 60% CD8+ cells, and all were CD3+ & HLA-DR+. NK cells comprised less than 5%. In clinical trials involving 12 cases receiving 35 infusions, the mean number of harvested T cells after 14 days culture was 3.5 x 10(10) (R = 1.6-6.8 x 10(10)), and the mean expansion index was 1560-fold (R = 409-4091). This method could be of benefit not only in immunotherapy but also for obtaining somatic cells from a small volume of blood for use in molecular or genetic analysis instead of having to perform EB virus transformation of B cells.