In vivo development of Theileria annulata: major changes in efferent lymphfollowing infection with sporozoites or allogeneic schizont-infected mononuclear cells

The object of these experiments was to study the pathogenesis and kinetics of Theileria annulata infection in the efferent lymph of the draining lymph nodes of calves. Efferent lymphatics of calves were cannulated prior to in fection with T. annulata sporozoite or an allogeneic schizont cell line. Po tentially lethal sporozoite challenge induced cell shut-down from days 4-6 and then a massive increase in output of blasting cells (both infected and non-infected) in the efferent lymph. The rate of lymph flow and total cell output increased to 5 to 10-fold from day 6 onwards. Sporozoites were never isolated from the efferent lymph. However, large numbers of parasite-infec ted cells were seen in efferent lymph from the sixth day of infection. The animals inoculated with an allogeneic T. annulata-infected cell line exhibi ted only a small increase in flow rate and cell output. Parasite-infected c ells of recipient origin were seen in efferent lymph from day 11 onwards. H owever, cells of donor origin were never isolated either from efferent lymp h or peripheral blood. Thus the parasite transferred from the inoculated do nor cell line to the cells of the recipient before schizonts appeared in ef ferent lymph.