PHYTOHEMAGGLUTININ RESPONSE OF RECIRCULATING AND NON-RECIRCULATING RAT LYMPHOCYTES

Rat lymphocytes of two types were obtained and their response to PHA was studied in cultures. Lymphocytes which recirculate between blood and lymph were collected from a thoracic duct fistula, and non-recirculating lymphocytes were obtained from the blood of rats that had been depleted of thoracic duct lymph for three days. Only recirculating lymphocytes could be stimulated by PHA to increase their RNA and DNA synthesis, although the presence of non-recirculating lymphocytes in the culture was necessary to obtain a maximal response. Non-recirculating lymphocytes had a high basal RNA synthesis in unstimulated cultures, and they seemed to survive better in three-day cultures than did recirculating lymphocytes. It is concluded that recirculating and non-recirculating lymphocytes behave different in vitro, and probably represent functionally separate cell groups. © 1969.