I region-restricted T cell line stimulated with hapten-treated syngeneic cells: selection of clones with reactivity for both allogeneic Ia determinants and self-I-A plus hapten.

The apparent switch in proliferative T cell reactivity which occurred in a B10 T cell line (B10(T4)) repeatedly stimulated with trinitrobenzene sulfonic acid (hapten)-treated syngeneic cells is described. This functionally heterogenous T cell population, apparently depleted of alloreactivity and strictly dependent on cells expressing syngeneic I-A and the hapten for its propagation, lost, after its 10th restimulation, the previously detected T cell functions, and expressed a new pattern of proliferative reactivity; this pattern included reactivity to self-I-A plus hapten as well as to untreated stimulating cells expressing certain allogeneic determinants. Analysis of reactivity of B10(T4) cells grown under limiting dilution conditions and of five clones of cells derived from B10(T4) indicated that the same T cells were reactive to both self-I-A plus hapten, and to a public I-A-mapped alloantigen possibly related to the serologically defined Ia.5 specificity.