Characterization of immunoglobulins eluted from hamster SV40 tumors

In order to determine if progressively growing tumors specifically bind antitumor antibody, which might play a role in blocking tumor specific cell-mediated immunity, low pH elutions were performed on autochthonous and transplantable SV40 tumors growing in situ for various lengths of time. Ouchterlony analysis revealed that IgG2 was present in all tumor eluates, while IgG1 was present only in eluates from tumors that grew in situ for more than sixty days. IgA and IgM were also found in most eluates but their presence did not correlate with duration of in situ growth. While no antibody to cell surface antigens could be detected, the eluates did possess antibody activity directed to the SV40 nuclear T-antigen. The tumor eluates did not block in vitro lymphocyte dependent microcytotoxicity of immune lymphocytes against cultured SV40 tumor cells. The biological role and significance of different classes of immunoglobulins bound to the surface of growing tumor cells is still poorly understood and requires further study.