Antigens of virus-induced tumors

Antigen(s) expressed on cultured cells of various species that crossreact with tumor antigens(s)

Antibodies eluted from a methycholanthrene induced sarcoma (MC-D) of strain 13 guinea pigs were examined for reactivity against 11 cultured cell lines derived from unrelated tumors and 11 cell lines originating from normal tissues of various species by radioimmunoassay. Six tumor-derived lines of mouse, hamster, rat, guinea pig and man and five "normal" cell lines of guinea pig, human and fish origin showed significant reaction.

In vitro immune responses to PPD, extracts from Raji cells and nasopharyngeal carcinoma biopsies in NPC leucocytes

Peripheral leucocytes from nasopharyngeal carcinoma (NPC) patients and control subjects, which included healthy subjects and patients with other cancers, have been tested against PPD and a panel of extracts from Raji cells and pooled NPC biopsies, using the blast transformation and the macrophage migration inhibition assays. The results of both assays indicated that the in vitro cell-mediated immune (CMI) responses to the Raji-cell extracts and NPC-biopsy extracts were associated with NPC. However, the peripheral leucocytes from NPC patients and control subjects responded similarly to PPD. These results are in general accord with the skin tests reported by Levine et al. (1976) and Ho, Ng and Kwan (1977b). The antigenic specificity of the NPC-associated CMI responses remains, however, to be resolved, as the extracts used in these or in the in vivo CMI studies were heterogeneous mixtures.

Detection of tumor-specific antigens in an equine sarcoid cell line

Indirect immunofluorescence and lymphocyte cytotoxicity experiments demonstrated the presence of a tumor-specific antigen(s) on the surface of cells from an equine sarcoid cell line (Mc1). Autologous serum (taken from the horse from which the Mc1 cells were derived) and sera from three other sarcoid-bearing horses revealed a similar membrane immunofluorescence when reacted with Mc1 cells, indicating the existence of cross-reacting antibodies. Results of serum colony inhibition experiments indicate that these antibodies are not cytotoxic. Incubation of Mc1 cells with autologous lymphocytes resulted in a toxicity to Mc1 cells, thereby demonstrating a cell-mediated immune reaction to autologous tumor cells.

Demonstration of cytotoxic antibodies in rabbits bearing tumors induced by Shope fibroma virus

The (51)Cr-release test was used to detect cytotoxic antibodies in adult rabbits bearing tumors induced by Shope fibroma virus. The following are the recommended experimental conditions: the infection of RK-13 cells with a multiplicity of 1 to 2 infectious units per cell for 48 hr, (51)Cr labeling of infected cells during the last 12 hr of incubation, sensitization of suspended labeled infected cells for 1 hr with immune serum, and quantitation of cell damage by the amount of (51)Cr released after 6 hr of incubation in the presence of complement. The immune sera reacted only with fibroma virus-infected cells but not with cells infected with vaccinia virus or herpesvirus type 1. Similarly, sera prepared against vaccinia virus and herpesvirus type 1 were not cytotoxic to fibroma virus-infected cells, although they were cytotoxic to cells infected with homologous viruses. The total antibody activity in sera of rabbits infected with Shope fibroma virus was detected first on day 7, gradually rose to its peak by day 23, and persisted at that level for at least 50 days. The 19S antibody was detected on day 7, reached peak titers by day 13, and disappeared by day 17. The 7S antibody was barely detectable on day 7, reached maximum titers on day 13, and remained high for at least 50 days. The tumors appeared on the 3rd day after virus inoculation, reached maximum size on day 13, and regressed completely by day 23.