Studies on ovine efferent lymph following infection with Toxoplasma gondii.

Cell output was monitored in efferent popliteal lymphatics of sheep following subcutaneous injection into the lateral tarsus of either 100 T. gondii tissue cysts or control inoculum. Sheep undergoing a primary infection developed a substantially increased lymphoblast output which reached a peak of more than 50 per cent of all cells. The majority of lymphoblasts did not contain Ig and may have been T cells. IgG antibody against T. gondii was detected in lymph by day 9. Animals with naturally acquired antibody to T. gondii developed a more rapid lymphoblast response to the parasite which, at its peak, accounted for 27.5 per cent of all cells. Many of these lymphoblasts contained Ig, presumably specific antibody, which, by increasing phagocytosis and intracellular killing of the T. gondii, would prevent multiplication and dissemination of the parasite.