Long-lasting functional unresponsiveness induced by a milk-transmitted Mls-1a-like superantigen

We have recently shown (Piazzon et al. (1994) J. Immunol. 153, 1553) that foster-nursing of BALB/c mice on F1 Mls-1bxa mothers induce the progressive deletion of V beta 6+ and 8.1+ T cells in 50% of the mice. Preceding clonal deletion, a state of functional inactivation of CD4+ T cells to Mls-1a and anti-V beta 6 antibodies was detected in young mice. In the present paper we show that foster-nursing of BALB/c mice on (BALB/cxAKR)FI mothers is able to induce alterations in T cell reactivity in the non-deletor mice. Lymph node cells from foster-nursed mice show a decreased proliferative level against anti-V beta 6 antibodies and a diminished response in MLR and in CTL assays. The proliferative responses to either OVA or Con-A are also reduced. This state of functional inactivation is detected even in 6-month-old foster-nursed mice. Thus, the transmission through milk of the Mls-1a-like superantigen correlates in the non-deletor mice with a long-lasting state of functional inactivation and a decreased immune reactivity.