T cell mediated cytotoxic immune reactivity of bone marrow reconstituted chimeric mice

The capacity of bone marrow reconstituted chimeric mice to mount sendai virus specific H-2 restricted as well as alloreactive cytotoxic T-cell responses has been investigated. Chimeras of the type a leads to (a x b)F1 and (a x b)F1 leads to a were used. In addition chimeras produced with (a x b)F1 mice grafted under the kidney capsula with a type parental thymus, thymectomised, lethally irradiated and reconstituted with either a, (a x b)F1 or b type bone marrow cells were tested. In agreement with the data of Zinkernagel and Bevan it was noted that virus specific T cells of semi-allogeneic chimeric mice are able to recognise virus antigens in the context of the MHC of the thymus in which they have maturated. The unexpected finding was that fully allogeneic chimeras were able to mount both alloreactive CTL and H-2 restricted, virus specific CTL. The H-2 restricted CTL detected were preferentially restricted to their own MHC type. In some animals also virus specific CTL restricted to the allogeneic thymus MHC type were observed. Data are also presented to indicate that longterm cultured bone marrow cells have the potential to repopulate lethally irradiated mice.