Normal mice were pretreated twice at an interval of 2 weeks with an
emulsion of TLA (Toxoplasma lysate
antigen), PLA (Plasmodium lysate
antigen) or both in LMO (light
mineral oil) or with a combination of the
emulsion and
Obioactin or Tp-LKs (Toxoplasma
lymphokines) as an
immunopotentiator. They were then given
Obioactin or Tp-LKs 3 and 25 days after the first treatment and were further given parasitized erythrocytes with 1 X 10(2)-10(4) P. berghei 2 weeks after the second treatment. Thirty (3/10, number of survival/number of examined) per cent of mice treated with TLA, 50 (5/10)% of those treated with a combination of TLA and Tp-LKs and 60 (6/10)% of those treated with a combination of TLA and
Obioactin survived as long as 20 days postinfection while none of untreated controls survived more than 15 days postinfection. Only 18.2 (2/11)% of mice treated with PLA or TLA + PLA survived and 20 (2/10), 18.2 (2/11) and 60 (6/10)% of those treated with TLA +
Obioactin, PLA +
Obioactin or TLA + PLA +
Obioactin survived throughout the experiment, respectively while none of controls survived more than 13 days postinfection. Five mice of each group were killed right before
infection, and 5, 10 and 15 days postinfection. In mice treated with TLA +
Obioactin, more macrophage phagocytosis and macrophage migration inhibition induced by sensitized T-cells were observed than in those treated otherwise. No appreciable differences were noted according to the method of treatment in blood examination values. Cross immunities between Toxoplasma and Plasmodium
antigens were tested by counter-immunoelectrophoresis and indirect fluorescent antibody technique. By using counter-immunoelectrophoresis, a specific precipitin line was observed between TLA and anti-PLA which was absorbed by mouse erythrocytes, leucocytes and liver
powder. By the indirect fluorescent antibody technique, anti-Plasmodium
IgM and
IgG titers were detected in sera from mice treated with TLA or TLA-
Obioactin before
infection.