The In Vivo Coating of Tumor Cells by Potentially Cytotoxic Antitumor Antibodies
Masking of cell surface antigens was first suggested as one of the mechanisms by which enhancing antibodies operate in a tumor bearing host (1). Such a masking, inferred also from studies showing that in vivo growing tumor cells are coated with immunoglobulin (Ig), is lately considered a key event in many alternative pathways by which the tumor escapes the immune reactivity of the host (2). This consideration is supported by the following indirect evidence: 1. Enhancement of tumor growth by immunoglobulin (Ig)-containing tumor eluates (3–4). 2. Blocking of in vitro cell mediated antitumor activity by tumor eluates, of human and animal origin (4–6). 3. Demonstration of an increased ability of human tumor cells to stimulate DNA synthesis in autochthonous lymphocytes following “unmasking” of tumor antigens (7). The association between tumor cell surface and Ig has been demonstrated directly (8). Yet it is not clear whether the coating of tumor cells by Ig and the masking of cell surface antigens is the very same phenomenon. This study was aimed to determine whether part of the Ig coating of Polyoma virus induced mouse tumor cells (SEYF-a, 9) consists of specific antibodies.
KeywordsAntigenic Determinant Cell Surface Antigen Rabbit Anti Mouse Antibody Cytotoxic Antibody Unlabelled Competitor
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