High levels of AR mRNA and protein were induced by synergy between TCR signals and signals that elevated cAMP or activated PKA. This contrasts with a previous report suggesting that both resting and anti-CD3 stimulated T cells significantly up-regulated AR in response to a cAMP agonist [40] . However, the enriched T cell population used in that study was purified by negative selection and very likely included basophils, which we have shown are potent producers of AR in response to IL-3 [31] . AR expression is also strongly enhanced by cAMP agonists in basophils (Y. Qi and T.R. Mosmann, unpublished data) and so it is possible that basophils may have produced the AR in response to the cAMP agonist without TCR stimulation.