       Document 0640
 DOCN  M9620640
 TI    Quantitation of endogenous mouse mammary tumor virus superantigen
       expression by lymphocyte subsets.
 DT    9602
 AU    Waanders GA; Lees RK; Held W; MacDonald HR; Ludwig Institute for Cancer
       Research, Lausanne Branch, University; of Lausanne, Epalinges,
       Switzerland.
 SO    Eur J Immunol. 1995 Sep;25(9):2632-7. Unique Identifier : AIDSLINE
       MED/96011878
 AB    Superantigens (SAg) encoded by endogenous mouse mammary tumor viruses
       (Mtv) interact with the V beta domain of the T cell receptor (TcR-V
       beta). Presentation of Mtv SAg can lead to stimulation and/or deletion
       of the reactive T cells, but little is known about the quantitative
       aspects of SAg presentation. Although monoclonal antibodies have been
       raised against Mtv SAg, they have not been useful in quantitating SAg
       protein, which is present in very low amounts in normal cells.
       Alternative attempts to quantitate Mtv SAg mRNA expression are
       complicated by the fact that Mtv transcription occurs from multiple loci
       and in different overlapping reading frames. In this report we describe
       a novel competitive polymerase chain reaction assay which allows the
       locus-specific quantitation of SAg expression at the mRNA level in
       lymphocyte subsets from mouse strains with multiple endogenous Mtv loci.
       In B cells as well as T cells (CD4+ or CD8+), Mtv-6 SAg is expressed at
       the highest levels, followed by Mtv-7 SAg and (to a much lesser extent)
       Mtv-8,9. Consistent with functional Mtv-7 SAg presentation studies, we
       find that Mtv-7 SAg expression is higher in B cells than in CD8+ T cells
       and very low in the CD4+ subset. The overall hierarchy in Mtv SAg
       expression (i.e. Mtv-6 > Mtv-7 > Mtv 8,9) was also observed for mRNA
       isolated from neonatal thymus. Furthermore, the kinetics of intrathymic
       deletion of the corresponding TcR-V beta domains during ontogeny
       correlated with the levels of Mtv SAg expression. Collectively our data
       suggest that T cell responses to Mtv SAg are largely controlled by SAg
       expression levels on presenting cells.
 DE    Animal  Antigen Presentation  B-Lymphocytes/*IMMUNOLOGY  Base Sequence
       CD4-Positive T-Lymphocytes/*IMMUNOLOGY  CD8-Positive
       T-Lymphocytes/*IMMUNOLOGY  Mammary Tumor Viruses, Mouse/*IMMUNOLOGY
       Mice  Molecular Sequence Data  Polymerase Chain Reaction  RNA,
       Messenger/ANALYSIS  Superantigens/*IMMUNOLOGY  T-Lymphocyte
       Subsets/IMMUNOLOGY  Thymus Gland/IMMUNOLOGY/METABOLISM  Transcription,
       Genetic  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

