Presence of hapten-bearing T cells in tolerance induced by DNP-isologous IgG

Abstract

When mice are made tolerant to the hapten DNP by intravenous injection of DNPisologous IgG, the hapten persists on the surface of antigen-binding cells (ABC) as long as the lymphocytes are tolerant. It is not known whether the hapten-bearing cells (HBC) are T cells, B cells, or both. Double-labelling experiments have been done to determine whether hapten-bearing cells are T cells or B cells. DNP-bearing cells from tolerant animals were detected by fluoresceinlabelled rat anti-DNP globulin. By labelling the same spleen cell suspension with rabbit anti-T-cell antiserum and rhodamine goat anti-rabbit serum, T cells which have DNP on their surface were detected since they bind both rhodamine and fluorescein. Using these techniques, it was demonstrated that 5 days after tolerance induction with 200 .tg DNP7IgG, almost all HBC are T cells. Fourteen days after injection of this same dose of tolerogen, the same number of hapten-bearing T cells were present in the spleens of these mice, but significant numbers of non-T-cell HBC are also present. When animals were made tolerant with 1 mg of DNP-IgG, only a small proportion of HBC were T cells. In animals receiving four weekly injections of 200 tg DNP-IgG, large numbers of hapten-bearing cells were found, but few HBC were T cells. Thus HBC from tolerant spleens can be T cells depending on the dose of tolerogen injected, and the time after tolerance induction. A significant proportion of the HBT cells have Ly 2 antigen on their surfaces, while others have Ly 1 antigen. Whether the hapten-bearing T cell is a suppressor cell, a tolerant helper cell, or an anti-idiotype-bearing cell is discussed.