Regulation of T cell-dependent autoantibody production by a γδ T cell line derived from lupus-prone mice

Abstract Lupus-prone (MRL×C57BL/6) F 1 mice lacking γδ T cells show more severe lupus than their T cell-intact counterparts, suggesting that γδ T cells down-modulate murine lupus. To determine the mechanisms for this effect, we assessed the capacity of γδ T cell lines derived from spleens of αβ T cell-deficient MRL/Mp- Fas lpr (MRL/ Fas lpr ) mice to down-regulate anti-dsDNA production generated by CD4 + αβ T helper cell lines and activated B cells from wild-type MRL/ Fas lpr mice. One line, GD12 (gd TCR + , CD4 − CD8 − ), had the capacity to reduce anti-dsDNA production in a contact-dependent manner. GD12 also killed activated MRL/ Fas lpr (H-2 k ) B cells, with less cytolysis of resting B cells than that generated by in comparison to cytokine-matched γδ T cell lines. In addition, GD12 also killed activated B cells derived from C57BL/6- Fas lpr (H-2 b ) or β 2 -microglobulin (β 2 M)-deficient MRL/ Fas lpr mice, suggesting cytolysis was neither MHC- nor CD1-restricted. Killing by GD12 was inhibited by anti-TNFα and anti-TNF-R1, and partially blocked by anti-gd TCR Fab fragments, but not by anti-FasL, anti-TNF-R2 (p75) or concanamycin A. IL-10 produced by GD12 also partially inhibited αβ Th1-dependent but not αβ Th2-dependent autoantibody production. These findings prove that we have identtified a γδ T cell line that suppresses autoantibody synthesis by αβ T-B cell collaboration in vitro.