No abstract

No abstract

The purpose of this study was to determine whether the UV-associated antigens present on tumors induced in mice by chronic UV irradiation could be induced by in vitro irradiation of cells that were already tumorigenic, or whether their occurrence was associated with the primary neoplastic transformation event. Cells of a nonantigenic, spontaneous fibrosarcoma cell line were exposed to UV radiation in vitro, were cloned, and were tested for antigenic properties. A large number of the clones obtained after UV irradiation of the fibrosarcoma cells were highly antigenic (20 of 39), whereas clones derived from unirradiated cultures were not (0 of 10). The antigenic variants did not induce cross-protection among themselves, but induced only variant-specific immunity in vivo. Several antigenic variants were tested for susceptibility to the action of UV-induced suppressor cells, which seem to recognize a common determinant shared among UV-induced tumors. The variants tested were indeed subject to the activity of the UV-induced suppressor lymphocytes. These results demonstrate that the unique antigenic properties exhibited by UV-induced murine skin cancers are also exhibited by cells exposed to UV radiation in vitro. In addition, they imply that the UV-associated antigens arise as a consequence of exposing cells to UV radiation and that they can occur independently of an initial neoplastic transformation event.

The purpose of this study was to examine the capacity of different clones derived from the same tumor to generate highly antigenic cells after in vitro exposure to UV radiation. Cells from the metastatic murine melanoma K1735 and clones of K1735 differing in metastatic potential were exposed to UV radiation in vitro, cloned, and tested for antigenic properties in vivo. Approximately half of the clones isolated after UV irradiation of parental K1735 melanoma cells were highly antigenic (five of nine). Similar treatment of cells of a nonmetastatic clone of K1735 generated clones that were all antigenic (nine of nine). In contrast, only one of nine clones derived from UV-irradiated cells of a highly metastatic clone of K1735 were antigenic. Clones derived from unirradiated cultures were not antigenic variants. The increased antigenicity of cells derived from UV-irradiated cultures did not correlate with an increase in expression of cell surface class I major histocompatibility complex antigens. These results demonstrate that the frequency of antigenic variant production after UV irradiation is an intrinsic property of the particular cell line used, and that even cloned cell lines derived from a single tumor differ in their ability to generate antigenic variants after UV irradiation. In addition, they indicate that the increased antigenicity is not necessarily due to a UV-induced increase in expression of cell surface class I histocompatibility antigens.