Expression of Mouse Mammary Tumor Virus Superantigen Accelerates Tumorigenicity of Myeloma Cells

AUTOR(ES)
FONTE

American Society for Microbiology

RESUMO

To investigate whether superantigen (SAG) from endogenous mouse mammary tumor virus functions as an immunogenic or a tumorigenic factor in tumor development, the BALB/c myeloma cell line FO was transfected with the SAG gene from the 3′ Mtv-50 long terminal repeat (LTR) open reading frame (ORF), the product of which was specific for Vβ6. All five transfectants expressing Mtv-50 LTR ORF mRNA showed stimulatory activity for Vβ6 T-cell hybridomas in vitro; this activity was inhibited by the addition of anti-Mtv-7 monoclonal antibody (MAb) or anti-major histocompatibility complex class II I-Ad and I-Ed MAb. All transfectants with the SAG gene grew more rapidly than did mock transfectants in BALB/c mice after subcutaneous inoculation, whereas all clones, including mock transfectants, grew equally well in athymic nude mice. A significant fraction of Vβ6 T cells selectively expressed activation markers, including CD44high, CD62Llow, and CD69high, and produced large amounts of interleukin 5 (IL-5) and IL-6 in BALB/c mice inoculated with transfectants. These results suggested that the expression of viral SAG enhances the tumorigenicity of a myeloma cell line through the stimulation of SAG-reactive T cells.

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