Heterogeneity of an anti-H-2 I-A response as determined by cloned T cell reactivity.

T lymphocytes activated against the I-Aq gene product in primary mixed leukocyte culture (MLC) exhibit an unusually strong cross-reactivity against all third-party stimulating strains tested in secondary MLC. Through the development of anti-I-Aq clones, this cross-recognition has been shown to result from the activation of a heterogeneous T lymphocyte population bearing receptors that recognize the I-Aq gene product differently, yet specifically. The determination of functional activities of the anti-I-Aq cloned cells, e.g., lymphokine production and ability to induce lethal graft-vs-host disease, suggested even further heterogeneity in T cells grouped according to their similar cross-reactive pattern.