Sensitization of Human Lymphocytes Against Autologous or Allogeneic Lymphoblastoid Cell Lines: Characteristics of the Reactive Cells

Normal human peripheral blood lymphocytes were sensitized to autologous or allogeneic lymphoblastoid cells in vitro. Purified T lymphocytes were found to be able to respond both by performing DNA synthesis and by functioning as killer cells. Surface marker analysis of blast‐transformed lymphocytes in the in vitro cultures showed a high proportion (around 50%) of blasts lacking any surface marker attributable to b or T blasts; such ‘null’ blasts have previously not been found in conventional mixed leukocyte culture or after phytohemagglutinin or concanavalin A activation Since the ‘null’ blasts could be shown to be produced in a high percentage from originally almost pure sheep erythrocyte(SRBC) binding lymphocytes and displayed a similar killing capacity per unit cell number is SRBC‐binding lymphoblasts, we consider the ‘null’ blast to be of T origin.