The cytotoxic T lymphocyte response in reticuloendotheliosis virus-infected chickens is mediated by αβand not by γδ T cells

Abstract

We induced a virus-specific cytotoxic T lymphocyte (CTL) response in B2 chickens by i.v. inoculation with 100 TCID 50 of the reticuloendotheliosis virus (REV). Chickens were sacrificed 7 days after the infection and cytotoxic activity of the spleen cells against various target cells was assayed in a 4 h 51Cr-release assay at an effector to target ratio of 100:1. In addition, T cell receptor (TCR) αβand TCR γδ cells were negatively selected from the REV-immune spleen cells and used as effector cells against REV-infected B2 target cells. (On average 40 % of spleen T cells express TCR γδ in the chicken.) By inhibition of the cytotoxic activity of the immune spleen cells against REV-infected syngeneic target cells with monoclonal antibodies specific for chicken CD3 and CD8 molecules, the effector cells could be identified as CD8 + T cells. The cytotoxic activity was MHC-restricted, as only syngeneic but not allogeneic REV-infected target cells were lysed by REV-immune spleen cells, and virus-specific, as no cytotoxic activity could be found using uninfected syngeneic target cells. When assaying the activity of the negatively selected, > 98 % pure αβ and γδ T cells, it was found that αβ T cells exerted virus-specific CTL activity ranging from 26 to 62 % specific 51Cr-release, while γβ T cells showed only 2–4 % 51Cr-release. These data indicate that REV-specific CTL response is mediated by αβ T cells and that γδ T cells are not involved in virus-specific CTL activity in the spleen of REV-infected chickens.