Abstract
Summary and Conclusions
The blood of rabbits immunized with various blood and tissue flagellates has been found to exert an inhibitory or lethal action on cultures of the homologous organisms. This effect was very marked on cultures of Trypanosoma cruzi and Leishmania donovani, but was slight on those of L. brasiliensis and L. tropica. These factors are associated with the blood serum, are thermostable at 56°C, but are partially destroyed at 70°C.
The inhibitory or lethal action is observed in vitro in a medium prepared with the immune whole blood or immune serum on which the homologous organisms are grown. The reaction takes place in 3 stages, viz.,
(1) The organisms lose their motility and become agglutinated.
(2) They round up and become markedly swollen.
(3) Finally, the internal structure undergoes hyalinization which ends in the death of the protozoon.
Complement is not necessary for this reaction. This inhibitory or lethal factor appears to differ from ablastin.
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