[Genetic selection of mice for quantitative responsiveness of lymphocytes to phytohemagglutinin]

A two-way selection was performed in mice according to the quantitative response of small lymphocytes to the mitogenic activity of phytohaemagglutinin (PHA). The response of inguinal lymph node cells of each mouse to an optimal dose of PHA was measured by 3H-thymidine incorporation using a micro-plate method. Starting from four outbred mouse strains we mated on the one hand mice getting the best response and on the other hand mice getting the poorest response. A progressive separation of the two lines was observed. At the 7th generation a 3-fold difference was found between the two lines. A similar interline difference was observed when concanavalin A (ConA) was used as mitogen. The separation of the two lines was also evident when spleen cells or thymus cells were cultured with PHA or ConA.