SERUM HEMOLYTIC-ACTIVITY OF BABESIA-GIBSONI-INFECTED DOGS - THE DIFFERENCE IN THE ACTIVITY BETWEEN SELF AND NONSELF RED-BLOOD-CELLS

The serum hemolytic activity of Babesia gibsoni-infected dogs varied w hen assayed with nonself red blood cells from different dogs, whereas it did not vary when assayed with red blood cells, irrespective of sel f or nonself, from a particular dog throughout the experiment. The var iety in activity determined with nonself red blood cells was not relat ed to the type of red blood cell by DEA, D and J systems. Serum hemoly tic activity with self red blood cells was different in the course of infection from that with nonself red blood cells, especially in the la te stage of infection, when the activity with self red blood cells dec reased more rapidly than that with nonself red blood cells. The result s indicate that the serum hemolytic activity of B. gibsoni-infected do gs determined with self red blood cells probably reflects the in vivo activity, suggesting that the rapid decrease in activity in the late s tage of infection is a way of acquired resistances for the host to rec over from hemolytic anemia in the infection. The facts that the hemoly tic activity increased by heating the serum at 56-degrees-C, that the osmotic fragility of red blood cells remained almost on the same durin g the course of infection and that Coobms' test for red blood cells of the infected animal was negative suggest that the immune-mediated hem olytic anemia is not a possible mechanism for the progressive and seve re anemia in B. gibsoni-infection. The present results support the pre vious notion that the increased serum hemolytic activity is at least o ne of the causes of anemia in canine B. gibsoni-infection.