Cell surface changes in alloantigen activated T lymphocytes

Abstract

MANY interactions which take place between T lymphocytes and other cells are presumably mediated at the level of the cell surface. In a mixed leukocyte culture (MLC), interaction between allogeneic lymphocytes results in transformation of the responding small T lymphocytes to large blast-like cells and their development into killer, helper¹ and suppressor lymphocytes². Some blasts subsequently revert to small memory or ‘secondary-type’ lymphocytes³. An important question is whether significant changes occur in T lymphocyte membrane proteins as a result of these interactions. We have attempted to answer this question by comparing iodine-labelled surface proteins of the following cells: T lymphocytes before stimulation, blast cells and small lymphocytes purified by lg velocity sedimentation from an MLC on day five, and reversion T lymphocytes following an additional 5 d of culture of the separated blast T lymphocytes. The results demonstrate that iodine-labelled components change during blast transformation and provide evidence for membrane differences between ‘secondary-type’ T lymphocytes and unsensitised cells.