Trypanosoma cruzi: advantages of isolating bloodstream trypomastigotes by the carboxy methyl cellulose method.

Bloodstream trypomastigotes were isolated from blood of A/Sn mice 7 d after infection with 10(5) Trypanosoma cruzi Y strain. Red blood cells were removed by centrifugation and hypotonic shock and platelets and leucocytes by passage through a carboxy methyl cellulose column. Binding of trypomastigotes to the resin was prevented by including 10% normal mouse serum in the eluting buffer. In such conditions, more than 90% of the parasites applied to the column were recovered, free of white blood cells and platelets. A comparative study of the pre- and post-separation trypomastigotes showed that both had the same infecting capacity, ability to evade destruction by the complement system, and antigenic profile.