Heterogeneity of signal requirements in T cell activation within a panel of XXXX proliferative T cell clones.

@entity1 @entity7508 @entity69 @entity460 @entity1199 @entity4996
Activation of T lymphocytes is initiated by receptor ligand interactions at the cell surface leading to the transduction of intracellular signals followed by the de novo synthesis and expression of T cell activation markers (including receptors for @entity1199 ( @entity1199 ) and @entity69 ), production of @entity7508 , and T cell proliferation. This requisite first step for activation of T lymphocytes can be mimicked in certain situations with a variety of stimuli. These include antibodies to certain integral membrane proteins, @entity4996 , and plant lectins that act as mitogens. In this paper, we report that at least two classes of @entity1 T cell clones can be distinguished based upon signal requirements necessary to induce proliferation. Although all clones analyzed expressed @entity1199 receptors and secreted @entity1199 after non-antigenic activation, one subset of clones did not proliferate in response to the same non-antigenic signals. In that subset, complete activation leading to proliferation required interaction of the T cell with specific antigen. The ability to subset these T cell clones into two groups did not correlate with phenotypic differences, source of the clone, nor with magnitude of intracellular @entity460 mobilization. By studying the stimulation requirements of these two subsets of @entity1 T cell clones through the use of specific antigen or antigen-independent stimuli, it was possible to demonstrate that different stimuli varied in their ability to induce steps of T cell activation. Analysis of reactivity of these clones to suboptimal stimulation allowed the definition of intermediate stages of T cell activation. Such intermediate stages might reflect a diversity of intracellular signaling pathways or a complexity of regulatory mechanisms distal to the events that allow intracellular @entity460 mobilization. Thus for the first time, it has been possible to study ordered events of T cell activation in non-transformed, antigen-dependent @entity1 T lymphocytes. The data presented in this paper suggest that T cell activation is not an all or nothing phenomenon, and there is an ordered sequence of events that can be differentiated based upon signal requirements at the T cell membrane.
