T-cell stimulation and regulation: with complements from CD46.

Crosslinking of CD46 and CD3 on naïve human CD4+ T-lymphocytes induces interleukin-10 secretion and granzyme B expression. These highly proliferative T-regulatory type 1-like T-regulatory T-cells (Tregs) can suppress an immune response. We propose that this process is important in the prevention of chronic inflammation such as at epithelial borders and in deactivation of a successful immune response. Relative to the latter, once a complement-fixing polyclonal antibody response has been mounted, in most cases, the pathogen will be rapidly destroyed. At this time, the C3b/C4b-bearing immune complexes could initiate the deactivation arm of an immune response by shutting down immunocompetent cells through CD46-generated T-cells. Herein, we review this pathway for the induction of Tregs, focusing on a role for the complement system and especially signaling through CD46 on human T-cells.