Human T cell lines with antigen specificity and helper activity.

Human T blasts, obtained by stimulation of peripheral blood mononuclear cells (PBM) with tetanus toxoid, diphtheria toxoid or Candida albicans, were expanded in long-term culture using alternate periods of antigen restimulation and growth in media containing interleukin 2. The cells gave a proliferative response only to the antigen originally used for stimulation. Such as response was strictly dependent upon the presence of autologous but not of allogeneic mitomycin C-treated mononuclear cells. When added to autologous PBM depleted of E-rosetting cells together with the specific antigen, the T blasts induced a polyclonal proliferation and differentiation of B cells. Allogeneic B cells were activated by antigen-stimulated T blasts only in the presence of irradiated mononuclear cells autologous to the responding T blasts. The above responses seemed not to be regulated solely by the release of soluble factors; apparently cell to cell interactions had to take place to obtain an efficient B cell activation.