Removal of phytohemagglutinin from conditioned medium by affinity chromatography

Supernatants of lymphocytes cultured with phytohemagglutinin (PHA-induced conditioned medium) are known to contain residual lectin. Studies with T cells specifically sensitized against a given antigen and maintained in culture by the T cell growth factor in conditioned medium may be hampered by the presence of PHA since the lectin could induce polyclonal activation of T cells. We developed a procedure for removing lectin from conditioned medium by affinity adsorption on porcine thyroglobulin-Sepharose. The affinity method was capable of removing detectable amounts of lectin since the mitogenic capacity for peripheral blood lymphocytes was lost after adsorption. In contrast, thyroglobulin-Sepharose adsorbed CM retained good mitogenic activity and growth-supporting capacity for human cultured T cells.