Differential reactivity of V beta 9 T cells to minor lymphocyte stimulating antigen in vitro and in vivo.

The monoclonal antibody (mAb) MR10-2 is specific for mouse T cells expressing the V beta 9 chain of T cell antigen receptor. This mAb reacts with 2% of peripheral T cells in a number of different strains of mice, but in mice expressing the minor lymphocyte stimulating (Mls)-1a antigen, V beta 9+ T cells recognized by MR10-2 are deleted. However, we failed to demonstrate the Mls-1 a antigen-specific response of naive, non-activated V beta 9 T cells in vitro. On the other hand, T cells activated initially with anti-V beta 9 (MR10-2) mAb in vitro are capable of responding to the Mls-1a antigen. These results demonstrate that Mls-1a reactivity of V beta 9 T cells depends on the activation state of the T cells, suggesting a differential activation requirement between naive, non-activated T cells and previously activated T cells.