A unique subpopulation of human suppressor autorosette-forming T cells was fractionated from peripheral blood of healthy donors and patients with various immune disorders. These cells have been maintained in long-term cultures and evinced suppressor activity in their supernatants. The study indicates the existence of a competitive relationship between the suppressor factors secreted by the cell lines and IL-2. It was found that impaired suppressor function can be related to a decrease in suppressors cell number, impaired function of individual suppressor cells, or failure to respond to active suppressor factors.