Tumour cell-antibody interactions. II. In vitro studies.

The interaction of L5178Y thymic lymphoma cells syngeneic to DBA/2 mice and of normal thymocytes with goat IgG antibodies was studied in vitro. Viable tumour and normal cells exerted a rapid, continuous and temperature-dependent destruction of antibody activity. Fractionation studies of culture supernatants from antibody-coated cells revealed that a significant portion of the antibody was completely degraded to amino acids. Tumour cells digested antibody more effectively than did normal lymphocytes. This observed degradation of antibody was most extensive at 37 degrees, significantly less at room temperature (23 degrees) and not detectable at 0 degrees. Undegraded antibody released from antibody-coated cells had also lost its antibody activity to a considerable extent. This was due to the formation of soluble antigen-antibody complexes, which was observed even at 0 degrees. Cells fixed with 10% formalin bound maximum amounts of antibody were incapable of digesting antibody even at 37 degrees and did not release immune complexes. These findings are of relevance to cancer immunodiagnosis and immunotherapy.