FIG. 1.

Killing of N. caninum-infected adherent cell targets by stimulated T-lymphocyte effectors from N. caninum-infected cow 562 (A) and cow 495 (B) was dose dependent, parasite specific, and consistent with MHC restriction. Graphs shown are from single chromium release cytotoxicity assays representative of three assays per cow. The percent specific lysis of infected autologous targets is significant (>3 SEM) compared to uninfected autologous targets and infected and uninfected heterologous target cells. Cow 495 effectors were determined to be CD4⁺ 99%, CD8⁺ <1%, and <1% γδ T lymphocytes by flow cytometry. Cow 562 effectors were determined to be CD4⁺ 86%, CD8⁺ 12%, and <1% γδ T lymphocytes by flow cytometry. Error bars indicate the SEM.