Abstract
In vitro lymphocyte transformation of guinea pig lymph node cells induced by tuberculin PPD was essentially eliminated by treatment with 5-bromo-2-deoxyuridine and light. The remaining cell population was still capable of producing blastogenic factor and further, the amount of blastogenic factor released was comparable to that from the intact population in the same interval of culture. This result favors the conception that cells producing blastogenic factor in response to antigen are distinct from the cells responding to the antigen by DNA synthesis and proliferation.