K cell activity of human palatine tonsillar lymphocytes increased by indomethacin

Tonsillar lymphocytes from individuals between the ages of 4 and 32 were found to have K cell activity by a plaque assay on chicken erythrocytes. The activity was lower than that of peripheral blood lymphocytes from normal individuals. The K cell activity of tonsillar lymphocytes could only be demonstrated when the cells were isolated in the presence of indomethacin. Prostaglandin E2 (PGE2) was shown to be liberated in tonsillar breis prepared in the absence of indomethacin but not in its presence. It is suggested that PGE2 in vitro inhibits K cell activity of tonsillar lymphocytes.