Multiple pathways for antigen-independent activation of a T helper hybridoma.
An important question in mitogen activation of T cells is whether the T cell must interact with a major histocompatibility complex product during the activation process. The T helper hybridoma AODH 7.1 is specific for human gamma globulin in the context of IEd, and when activated secretes interleukin 2. The mitogen concanavalin A (Con A) can activate AODH 7.1 cells directly, but two other standard T cell mitogens, phytohemagglutinin (PHA) and neuraminidase-galactose oxidase, cannot. However, Con A, PHA and neuraminidase-galactose oxidase could all activate AODH 7.1 when presented on various cloned class II+ cell lines. There was an absolute requirement for the presentor cell to be class II+, and the activation signal on mitogen-treated class II+ presentor could be blocked by monoclonal antibody to the class II antigens. To determine if class II molecules were absolutely required for the presentation of a mitogen activation signal we used class II- LtK- L cells and two LtK- cell class II gene transformants as presentor cells. Only the class II+ transformants, but not the class II- LtK- cells, could present either Con A or PHA. The class II requirement cannot be bypassed through provision of soluble factors. However, when Con A was used to activate AODH 7.1 cells directly, it appeared to be acting in a transmembrane fashion. It was not the case that AODH 7.1 cells were responding to Con A on a neighboring AODH 7.1 cell, and no class II antigens were involved. These results are consistent with the idea that different routes of activation exist for T cells, at least at the level of signal recognition.
D000818:Animals; D000911:Antibodies, Monoclonal; D002460:Cell Line; D003208:Concanavalin A / Q000494:pharmacology; D005692:Galactose Oxidase / Q000494:pharmacology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006825:Hybridomas; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D009439:Neuraminidase / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D014466:Ultraviolet Rays
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2; D010835:Phytohemagglutinins; D003208:Concanavalin A; D005692:Galactose Oxidase; D009439:Neuraminidase