Release of the lymphokine osteoclast activating factor requires cyclic AMP accumulation.

The bone resorbing lymphokine osteoclast activating factor (OAF) is released by lymphocytes activated by phytohemagglutinin (PHA). In this study we have found that release of OAF by activated lymphocytes is dependent on cyclic AMP (cAMP). OAF release is preceded by cAMP accumulation in the lymphocytes, and when cAMP accumulation is impaired by treatment of activated leukocytes with indomethacin, OAF is not released. OAF release in these cultures is restored by the addition of agents that mimic or increase lymphocyte cAMP content by different mechanisms. When activated purified lymphocytes that do not release OAF by themselves were cultured with these agents, OAF appeared in the culture media. These results suggest that cyclic AMP accumulation in lymphocytes is required for OAF to be released after activation.