Polyclonal induction of IgG antibody forming cells by stimulation with Actinomyces viscosus T14V.

Abstract

Actinomyces viscosus has been shown to possess the potential for polyclonal B cell activation (PBA), but this activation mechanism is still not well understood. In this report, the T cell and/or macrophage requirement for PBA and the development of IgG producing plasma cells were investigated in the murine system by using an ultrasonicated extract from A. viscosus T14V (Av. sup). The results were as follows: 1. Av.sup activated B cells polyclonally without any participation of T cells and macrophages. 2. Av.sup could induce IgG as well as IgM antibody forming cells (AFC) polyclonally. IgG AFC were induced from surface IgG‐positive (sIgG+) B cells (memory B cells, which had been immunized with antigens), but not from sIgG− B cells. Therefore, circulating memory B cells may be activated by microbial components at periodontally diseased sites and these may contribute to the formation of an IgG‐producing B cell‐rich lesion.