RADIOLOCALIZATION OF XENOGRAFTED HUMAN-MALIGNANT MELANOMA BY A MONOCLONAL-ANTIBODY (9227) TO A MELANOMA-ASSOCIATED ANTIGEN IN NUDE-MICE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 45  (9) , 4150-4155
Abstract
A murine monoclonal antibody (9.2.27), directed to a MW 250,000 glycoprotein-chondroitan sulfate proteoglycan complex, was radiolabeled with 125I and assessed for radiolocalization in tumor and normal tissues of nomal and tumor-bearing nude mice. The 125I-9.2.7 localized in vivo preferentially in MW 250,000 antigen-expressing human melanomas (FMX-Met, SESX) but not in low antigen-expressing tumors (LOX-L) xenografted in nude mice. The imaging of tumor cells was positively correlated with the antigen density of the various melanoma cell lines as measured by flow cytometry. The nonspecific immunoglobulin RPC-5 of the same IgG2a subclass as 9.2.27 did not specifically localize to xenografts of melanoma. The total amount of 125I-9.2.27 accumulated in the tumor was directly correlated with tumor size. However, the specific radioactivity (cpm/g) in smaller tumors was higher than that in larger tumors. Nonspecific uptake and circulating antibody levels differed between normals and tumor-bearers. The organs of the reticuloendothelial system of normal mice accumulated more labeled antibody than did those of tumor bearers, and conversely, tumor bearers had higher levels of circulating labeled antibody in tumor bearers was still monomeric but had not detectable antigen-binding capacity.

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