Abstract: The present invention provides vaccines and a means of vaccinating a mammal so as to prevent or control specific T cell mediated pathologies or to treat the unregulated replication of T cells. The vaccine is composed of a T cell receptor (TCR) or a fragment thereof corresponding to a TCR present on the surface of T cells mediating the pathology. The vaccine fragment can be a peptide corresponding to sequences of TCRs characteristic of the T cells mediating said pathology. The vaccine is administered to the mammal in a manner that induces an immunologically effective response so as to affect the course of the disease. The invention additionally provides specific &bgr;-chain variable regions of the T cell receptor, designated V&bgr;6.2/3, V&bgr;6.5, V&bgr;2, V&bgr;5.1, V&bgr;13 and V&bgr;7, which are central to the pathogenesis of multiple sclerosis (MS).

Abstract: Laboratory non-human animals in which the immune system of a donor is induced in and thrives in vivo and expresses the immune response of the donor animal in a recipient non-human animal of a different species than the donor, and wherein malignant immune system cells of the donor can be induced in the recipient non-human animal by injection of non-malignant donor into the recipient are disclosed.

Abstract: Laboratory non-human animals in which the immune system of a human donor is induced in and thrives in vivo and expresses the immune response of the human donor in a recipient non-human animal, and wherein malignant immune system cells of the human donor can be induced in the recipient non-human animal by injection of non-malignant donor cells into the recipient are disclosed.