Anti‐ovarian carcinoma anti‐T3 heteroconjugates or hybrid antibodies induce tumor cell lysis by cytotoxic T‐cells

In the perspective of therapeutic in vivo targeting for T‐cell attack, the monoclonal antibody (MAb) Mov18, selected for its restricted reactivity with human ovarian carcinoma, and an anti‐T3 MAb were used to produce heteroconjugate or hybrid antibodies derived by fusion of relevant hybridomas. Specificity and activity of bispecific MAbs were analyzed by solid‐phase RIA, immunofluorescence and a ⁵¹Cr‐release assay on the ovarian carcinoma cell line OVCA 432, which expresses the relevant tumor‐associated antigen, and on several irrelevant tumor cell lines. Both reagents efficiently promoted, at ptcomolar concentration, target cell lysis by cytotoxic T‐cell (CTL) clones. Although the pattern of tumor cell lines which were lysed was wider than that predicted by binding studies, further studies using a double‐determinant immunoradiometric assay confirmed the specificity of MAb targeting. Analysis of reagents indicated that the hybrid MAb was superior to the heteroaggregate as far as purification recovery and storage stability were concerned. Besides CTL clones, peripheral blood lymphocytes could also be used as cytolytic effectors, provided that a suitable in vitro activation scheme was used.