Abstract
Blood lymphocytes were prepared from 6 patients at various time intervals after the onset of tularemia and from 10 subjects after vaccination against this disease. Lymphocytes were also prepared from subjects who had been vaccinated 1 and 2 years previously. The lymphocytes were incubated in the presence of membranes of the vaccine strain. Lymphocytes obtained 2 weeks or later after onset of the disease responded to the membranes with increased deoxyribonucleic acid synthesis, whereas lymphocytes obtained earlier than 2 weeks after onset did not respond. Lymphocytes of the vaccinated subjects did not respond to the membranes of the vaccine strain before vaccination. Two to 4 weeks after vaccination lymphocytes from six of the vaccinees yielded a high response, and this response was consistently high for several months. Lymphocytes from four of the vaccinated individuals responded to a low extent only, and this was consistently low for several months. Lymphocytes from individuals vaccinated 1 year before testing responded to a similar extent to the membranes, as did lymphocytes from those who had been vaccinated 1 month previously. Lymphocytes from individuals vaccinated 2 years previously, however, showed a diminished response to the membranes. There was no correlation between titer of agglutinating antibodies and magnitude of lymphocyte reactivity.