FLOW CYTOMETRIC ANALYSIS OF T-CELL RESPONSE IN MICE INFECTED WITH COWDRIA-RUMINANTIUM

A 3-fold increase in the numbers of Lyt-2+ T cells in the circulating blood of mice infected and re-infected with the Welgevonden stock of C owdria ruminantium, as determined by flow cytometry, is supportive evi dence that immunity in heartwater is cell-mediated. The rise in Lyt-2 cells only after re-infection of the mice is further evidence that th e development of immunity in heartwater is dependent on the unhindered and adequate replication of C. ruminantium.