Lymphocyte stimulation by allogeneic and autochthonous cultured lymphoid cells

The ability of allogeneic and autochthonous lymphoid cells maintained in long-term culture and three-day cultured PHA-stimulated autochthonous lymphocytes to stimulate fresh peripheral lymphocytes was investigated via the one-way mixed lymphocyte test. Long-term lymphoid cell lines stimulated fresh allogeneic peripheral lymphocytes as measured by DNA incorporation. Although autochthonous lines were usually not stimulatory, several experiments indicate that fresh peripheral lymphocytes may be stimulated by autochthonous long-term lines and phytohemagglutinin-transformed autochthonous lymphocytes. The major histocompatibility antigens were identical in fresh donor cells and autochthonous long-term lymphoid cell lines as demonstrated by standard cytotoxicity methods. Although the reason for this stimulation is not certain, the most likely possibility is the production of a blastogenic factor by these cell systems.