Lymphocyte-transforming activity of homologous and heterologous antisera to rabbit leucocytes.

Two out of nine rabbits receiving a course of immunization with homologous leucocytes produced antisera which caused blast formation and stimulated DNA synthesis of donor lymphocytes . Of the seven rabbits which failed to produce active antisera three had received only a short immunization course. The active antisera `transformed' lymphocytes from some rabbits but not those of others. This stimulatory effect was not related to the red cell types or the γ-globulin allotypes of the rabbits. Heterologous antisera raised to rabbit leucocytes in rats and guinea-pigs were cytotoxic to rabbit leucocytes and also caused leucoagglutination but never stimulated DNA synthesis and blast formation.