A KINETIC-STUDY ON THE DELETION OF THYMIC, PERIPHERAL, AND GUT-ASSOCIATED V-BETA-6(-CELLS IN AN MLS-1(B) BALB() T)C COLONY INFECTED WITH ANEXOGENOUS MOUSE MAMMARY-TUMOR VIRUS/

Mls-1a expression results in the deletion of T cells bearing Vbeta6 ch ains of the TCR. However, Vbeta6+ T cells are also deleted in Mls-1b B ALB/c mice that have been infected with an exogenous mouse mammary tum or virus (swiss mice) via maternal milk intake, and whose open reading frame region is markedly similar to that of the provirus Mtv-7. In th is report we describe the kinetics of Vbeta6+ T cell deletion in the t hymus, spleen, lymph nodes, and gut-associated lymphoid populations of these BALB/c mice from the early weeks of life to 6 mo of age. Deleti on of Vbeta6+ T cells within the CD4+ T cell population was more obvio us in the thymus than in the spleen at 8 wk of age. However, the earli est incidence of deletion was observed in the gut intraepithelial lymp hocyte population at 5 wk of age. Furthermore Mtv-7 (SW) transcripts w ere only found in the gut in the first wk of life, whereafter they cou ld be detected in the thymus, spleen, and lymph nodes. This report sug gests that after entering the intestinal tract of host mice, mouse mam mary tumor virus (swiss mice) is subsequently transferred to the thymu s and peripheral lymphoid organs resulting in the deletion of CD4+Vbet a6+ T cells in that order.