Cell-mediated hypersensitivity in guinea-pigs infected with toxoplasms gondii.

This investigation demonstrated delayed hypersensitivity by macrophage migration inhibition (MMI) and skin-testing (ST) at 4, 8, 12, and 17 weeks and by lymphocyte transformation (LT) at 4, 12, and 17 weeks after infection of guinea-pigs (GP) with Toxoplasma gondii (C-37 strain). MMI and LT were both most pronounced at 4 and 17 weeks post-infection. GP immunized with toxoplasmin in complete Freund's adjuvant (CFA) demonstrated positive blast transformation and ST, but GP immunized with phosphate buffered saline in CFA did not. MMI was demonstrated with both immunizing preparations. Positive dye test and indirect hemagglutination test titers from 4 through 17 weeks were found.