Polyethylene glycol-modified concanavalin A as an effective agent to stimulate anti-tumor cytotoxicity

The jack bean lectin, concanavalin A (Con A), was modified with 2,4-bis[O-m ethoxypoly(ethylene glycol)]-6-chloro-s-triazine, activated PEG(2), to form PEG-Con A. The immunoreactivity of PEG-Con A towards anti-Con A antibodies was reduced by increasing the degree of modification of amino groups in th e Con A molecule. PEG-Con A had a complete reduction of the immunogenicity in mice and prolonged the clearance-time in blood. Although the mitogenic a ctivity of Con A towards murine spleen cells was reduced by the conjugation with activated PEG(2), the administration of PEG-Con A to mice enhanced th e anti-tumor cytotoxicity of peripheral lymphocytes against melanoma B16 ce lls.