Dynamic alterations in some surface properties of freshly explanted Moloney lymphoma cells

The relationship of membrane antigens on 141 (NZB) and EL4 (C57BL) lymphoma cells as demonstrated by antibody-induced resistance to complement-mediated cytotoxicity

We have studied the ability of various antisera to induce resistance to complement-dependent lysis (CdL) (lysostripping) of surface antigens of B and T lymphoma cells. Alloantisera, xenoantisera, as well as anti-Rauscher-leukemia virus (RLV) antisera, were used. Whereas all antisera could induce resistance to CdL mediated by the same serum that served for lysostripping (autolysostrip), only some of the tested antisera could induce resistance to CdL by other antisera (co-lysostrip). In some combinations co-lysostrip was unidirectional, i.e., in a pair of antisera, one induced autolysostrip as well as co-lysostrip, whereas the other antiserum induced autolysostrip only. In other combinations co-lysostrip was reciprocal. These investigations do not support the possibility that viral components and alloantigenic determinants are associated on mouse lymphoma cells.

Tumor bound immunoglobulins: the relationship between the in vivo coating of tumor cells by potentially cytotoxic anti-tumor antibodies, and the expression of immune complex receptors

In this study we investigated the relationship between binding of anti-tumor antibodies by polyoma-virus-induced SEYF- a tumor cells and the expression of immune-complex receptors on these cells. It was shown that in vivo propagated cells became progressively coated with IgG. The increase in the IgG coating of SEYF-a cells, occurring during the second week of propagation, was directly correlated with an increase in the coating of cells with potentially cytotoxic anti-tumor antibodies. The activity of these antibodies was demonstrated by cell lysis following addition of exogenous complement. Cell populations propagated in vivo for longer periods (3 weeks or more) became less sensitive to exogenous complement although their IgG coating remained high, and although higher titers of anti-tumor antibodies could be eluted from them. This indicated that antibodies coating young tumor cell populations have the capacity to activate complement whereas those coating older tumor cell populations are incapable of complement activation. Previous findings that SEYF-a cell populations are able to bind unrelated immune complexes were confirmed in the present study. We also found that the capacity of these populations to bind such unrelated complexes decreased with propagation time in vivo. The involvement of anti-tumor antibodies in this phenomenon was indicated by the finding that such antibodies inhibited binding of unrelated immune complexes by young cells but not by old cells. Furthermore, treatments causing dissociation of Ig from the cell surface restored, to some extent, the capacity of anti-tumor antibodies to inhibit immune complex binding by old SEYF-a populations.

The effect of short-term culture on the sensitivity of MDAY murine tumor cells tolysis mediated by normal rabbit serum

Freshly explanted MDAY murine tumor cells are sensitive to lysis mediated by fresh normal rabbit serum. The sensitivity, which increases with the age of the tumor, is rapidly lost upon short-term culture, and takes place at 37 degrees C but not at 4 degrees C. Cellular components released into the medium during short-term culture are capable of eliciting xenogeneic antibodies that mediate complement-dependent lysis of such cells.