Effects of tobacco glycoprotein (TGP) on the immune system. I. TGP is a T-independent B cell mitogen for murine lymphoid cells.

It has been shown that tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein antigen purified from cured tobacco leaves, is mitogenic for lymphoid cells in the spleen, peripheral blood, and bone marrow, but not for thymus cells. The proliferative response is not reduced by treatment of spleen cells or peripheral blood lymphocytes with anti-Thy-1.2 and complement, and spleen cells from the congenitally athymic (nu/nu) CD-1 proliferate as vigorously in response to TGP as do spleen cells from their heterozygous nu/+ littermates. In addition, TGP induces differentiation of mouse spleen cells into antibody-secreting cells, the majority of which secrete IgM, and the remainder mainly IgG and a few IgA. The differentiation into antibody-secreting cells induced by TGP occurs with spleen cells from nu/nu mice. It is concluded that TGP is a T-independent B cell mitogen for mouse lymphoid cells. On the basis of the ability of spleen cells from the LPS-nonresponder C3H/HEJ mice to respond to TGP with proliferation and differentiation into antibody-secreting cells, it is concluded that the effects of TGP are distinct from those of LPS and cannot be due to contamination of the TGP preparation with LPS.