Surface Antigens on Transplantable Tumor Cell Lines Producing Mouse Type C Viruses

Abstract

A variety of transplantable mouse tumor lines were shown to contain murine type C viruses and virus-associated antigens. The type of virus isolated and antigens detected could not invariably be correlated with the original method of tumor induction, but testing of the majority of tumor lines for infectious virus at various levels of in vivo or in vitro passage yielded isolates that were consistent in tissue culture host range for each tumor. In contrast, during the course of in vivo transplantation, some of the lines underwent considerable change in the pattern of virus-associated cell-surface antigens. When the transplanted tumor lines were placed into culture, all showed some alteration in the detectable surface antigens. Upon retransplantation and passage of the cultured cells in mice, the surface antigens gradually returned to the original in vivo patterns and occasionally acquired additional type C virus-associated antigens not detected in the original tumor line. To test for association of antigens with infectious virus, appropriate tissue culture cell lines were infected with the viruses isolated from the tumors. In these infected indicator cells, some new virus-associated cell-surface and virion evelope antigens were detected, but the complete array of antigens found in the original tumor lines was not acquired. These findings indicated the presence of several different type C viruses in long transplanted cell lines and demonstrated that environmental and host cell factors may have major influences on expression of virus-associated antigens.

Studies on the nature of the cell surface antigen reacting with cytolytic T lymphocytes in murine oncornavirusinduced tumors

“…This might explain at least some of the discrepancies observed between the results of different groups. It should be noted that unexpected serologically defined specificities, including FMR, appear frequently on transplanted lymphomas as has been emphasized recently b y Aoki et al [40]. It is therefore absolutely necessary t o regularly control the behavior of target cells not only in cell-mediated immunity but also serologically, in order t o avoid possible misinterpretation.…”

In vitro elicitation of cytotoxic response against a nonimmunogenic murine tumor by allosensitization

“…In the course of passage, tumor lines may undergo phenotypic and antigenic changes [1,6,10,14,17,18,28] which are not necessarily associated with the neoplastic state of the original tumor cell. In an attempt to minimize the gross artifacts that might be found with highly immunogenic or long-passaged tumor lines, and to establish a model system more relevant to 'spontaneously' arising neoplasms, we decided to explore the cytotoxic response against a nonimmunogenic X-irradiation-induced lymphoma which has been maintained in culture for only a limited period of time.…”

Nature and complexity of the FMR antigenic system

“…On the other hand, group-specific antigens common to all the murine type C viruses including endogenous viruses, could be involved, as recently suggested by Nowinski et al [12]. Finally, it must be recalled that the expression of VCSA on FMR+ tumors varies greatly with time [22] so that the antigenic specificities detected by any given "anti-FMR' antiserum should be defined using a large panel of FMRf and FMR-target cells. Very careful conclusions must be drawn from any experiments performed with a given anti-FMR antiserum, tested against a precise tumor cell, in a given laboratory.…”