Studies on thymus products. VI. The effects of cyclic nucleotides and prostaglandins on rosette‐forming cells. Interactions with thymic factor

Abstract

AbstractCyclic AMP, its dibutyryl derivative and prostaglandins, PGE1 and PGE2, do not modify the numbers of rosette‐forming cells (RFC), but they do alter these cells' sensitivity to in vitro inhibition by azathioprine (AZ) and anti‐theta serum (ATS). In thymectomized mice, cyclic nucleotides and prostaglandins mimic the action of the thymic factor contained in thymic extracts and in normal serum, correcting the low spleen RFC sensitivity to AZ and ATS induced by thymectomy. Moreover, the mixture of infraliminal active doses of cyclic AMP and of thymic extracts (or normal mouse serum) also gives this effect. In normal mice, the nucleotides (but not prostaglandins) lower the AZ and ATS sensitivity of RFC, which remains insensitive to thymic extracts. Theophylline and isoproterenol have effects similar to those of cyclic AMP, a result in accord with their postulated interactions with the adenyl‐cyclase system. Noncyclic AMP and cyclic GMP show no effect in the RFC assay system at doses 10–100 times higher than active doses of cyclic AMP. Other vasoactive compounds, including epinephrine, phentolamine, propanolol, and angiotensin, do not show any effect on RFC.