Monoclonal antibodies to human colorectal tumor-associated antigens: improved elicitation and subclass restriction

Monoclonal antibodies to tumor-associated antigens (TAA) of human colorectal cancer were elicited using immunosorbents of lectins combined with peripheral protein extracts of xenografted colon adenocarcinoma. This method of immunization was compared with whole cells from surgical specimens and to crude membranes from xenografted tumors. The immunosorbent immunogens were superior to the other immunogens in three ways: (1) the number of hybrids reactive with colon tumor cells or extracts, but not with lymphoid cells or extracts, (2) the number of stable hybrids after cloning, and (3) the number of hybridoma clones reactive with tissue sections of colon tumors, but not normal colonic mucosa. In addition, lectin immunosorbents elicited primarily IgG antibodies, especially IgG3, with almost 50% of the clones of interest reacting to seemingly less immunogenic glycoproteins. The improved elicitation of monoclonal antibodies to TAA by the use of lectin immunosorbents and peripheral protein extracts has considerable potential for generating reagents useful in diagnosis and therapy of human tumors.