Lymphocyte transformation in the dog: response of lymphocytes from normal and immune dogs to phytohemagglutinin, coccidioidin, and purified-protein derivative.

Antigen- and mitogen-induced in vitro transformation of dog lymphocytes was quantitated by pulse labeling with 3H-thymidine (3H-TdR). Dosages of antigen and duration of incubation were varied to determine the dose and incubation time that would allow a clear distinction between sensitized and nonsensitized dogs. Each of the 2 antigens tested, coccidioidin and purified protein derivative of tuberculin, induced a higher rate of 3H-TdR incorporation in lymphocyte cultures from dogs immunized to the homologous antigen than in lymphocyte cultures from dogs immunized to either the heterologous antigen or no antigen. Lymphocyte cultures from all dogs showed a high rate of 3H-TdR incorporation in response to phytohemagglutinin stimulation. Sequential lymphocyte transformation tests were done on 4 dogs immunized with either Calmette-Guérin bacillus alone or Calmette-Guérin bacillus in Freund's complete adjuvant. A positive response to purified protein derivative became evident in all 4 dogs 11 days after immunization and peaked at 18 days after immunization.