My. Braun et al., T-CELL RECEPTOR V-BETA REPERTOIRE IN MICE LACKING ENDOGENOUS MOUSE MAMMARY-TUMOR PROVIRUS, European Journal of Immunology, 25(3), 1995, pp. 857-862
When endogenous mouse mammary tumor virus (MMTV) superantigens (SAg) a
re expressed in the first weeks of life an efficient thymic deletion o
f T cells expressing MMTV SAg-reactive T cell receptor (TcR) V beta se
gments is observed. As most inbred mouse strains and wild mice contain
integrated MMTV DNA, knowing the precise extent of MMTV influence on
T cell development is required in order to study T cell immunobiology
in the mouse. In this report, backcross breeding between BALB.D2 (Mtv-
6, -7, -8 and -9) and 38CH (Mtv(-)) mice was carried out to obtain ani
mals either lacking endogenous MMTV or containing a single MMTV focus,
i. e. Mtv-6, -7, -8 or -9. The TcR V beta chain (TcR V beta) usage in
these mice was analyzed using monoclonal antibodies specific for TcR
V beta 2, V beta 3, V beta 4, V beta 5, V beta 6, V beta 7, V beta 8,
V beta 11, V beta 12 and V beta 14 segments. Both Mtv-8(+) mice and Mt
v-9(+) mice deleted TcR V beta 5+ and V beta 11(+) T cells. Moreover,
we also observed the deletion of TcR V beta 12(+) cells by Mtv-8 and M
tv-9 products. Mtv-6(+) and Mtv-7(+) animals deleted TcR V beta 3(+) a
nd V beta 5(+) cells, and TcR V beta 6(+), V beta 7(+) and V beta 8.1(
+) cells, respectively. Unexpectedly, TcR V beta 8.2(+) cells were als
o deleted in some backcross mice expressing Mtv-7. TcR V beta 8.2 reac
tivity to Mtv-7 was shown to be brought by the 38CH strain and to resu
lt from an amino acid substitution (Asn --> Asp) in position 19 on the
TcR V beta 8.2 fragment. Reactivities of BALB.D2 TcR V beta 8.2 and 3
8CH TcR V beta 8.2 to the exogenous infectious viruses, MMTV(SW) and M
MTV(SHN), were compared. Finally, the observation of increased frequen
cies of TcR V beta 2(+), V beta 4(+) and V beta 8(+) CD4(+) T cell sub
sets in Mrv-8(+) and Mtv-9(+) mice, and TcR V beta 4(+) CD4(+) T cells
in Mtv-6(+) and Mtv-7(+) mice, when compared with the T cell repertoi
re of Mrv(-) mice, is consistent with the possibility that MMTV produc
ts contribute to positive selection of T cells.