Maarten Zijlstra

Germ-line transmission of a disrupted β2microglobulin gene produced by homologous recombination in embryonic stem cells

MAJOR histocompatibility complex (MHC) class I molecules are integral membrane proteins present on virtually all vertebrate cells and consist of a heterodimer between the highly polymorphic α-chain and the β2microglobulin (β2-m) protein of relative molecular mass 12,000 (ref. 1). These cell-surface molecules play a pivotal part in the recognition of antigens, the cytotoxic response of T cells, and the induction of self tolerance1,2. It is possible, however, that the function of MHC class I molecules is not restricted to the immune system, but extends to a wide variety of biological reactions including cell–cell interactions. For example, MHC class I molecules seem to be associated with various cell-surface proteins, including the receptors for insulin, epidermal growth factor, luteinizing hormone and the β-adrenergic receptor3–6. In mice, class I molecules are secreted in the urine and act as highly specific olfactory cues which influence mating preference7, 8. The β2-m protein has also been identified as the smaller component of the Fc receptor in neonatal intestinal cells9, and it has been suggested that the protein induces collagenase in fibrob-lasts10. Cells lacking β2-m are deficient in the expression of MHC class I molecules, indicating that the association with β2-m is crucial for the transport of MHC class I molecules to the cell surface1. The most direct means of unravelling the many biological functions of β2-mis to create a mutant mouse with a defective β2-mgene. We have now used the technique of homologous recombination to disrupt the β2-mgene. We report here that introduction of a targeting vector into embryonic stem cells resulted in β2-mgene disruption with high frequency. Chimaeric mice derived from blastocysts injected with mutant embryonic stem cell clones transmit the mutant allele to their offspring.

β2-Microglobulin–Deficient NOD Mice Do Not Develop Insulitis or Diabetes

The role of CD8+ T-cells in the development of diabetes in the nonobese diabetic (NOD) mouse remains controversial. Although it is widely agreed that class II-restricted CD4+ T-cells are essential for the development of diabetes in the NOD model, some studies have suggested that CD8+ T-cells are not required for β-cell destruction. To assess the contribution of CD8+ T-cells to diabetes, we have developed a class of NOD mouse that lacks expression of βxs2-microglobulin (NOD-B2mnull). NOD-B2mnull mice, which lack both class I expression and CD8+ T-cells in the periphery, not only failed to develop diabetes but were completely devoid of insulitis. These results demonstrate an essential role for CD8+ T-cells in the initiation of the autoimmune response to β-cells in the NOD mouse.

Control of γδ T‐Cell Development

T cells expressing the yd T-cell receptor have been found in all vertebrate species examined. While it appears likely that these cells have an important physiological specificity in the immune system, their role is only beginning to be unravelled. Unusual features of the ontogeny, tissue tropism, and receptor diversity of yd cells suggest that there exist subtypes of these cells with distinctive functions, which differentiate in a highly ordered pattem intrathymically. This review will emphasize issues of yS T-cell differentiation and development in the mouse, highlighting work from our laboratory. More comprehensive reviews of yd cells and their receptors can be found elsewhere (Allison & Havran 1991, Allison & Raulet 1990, Brenner et al. 1988, Raulet 1989).

Role of CD8+αβ T Cells in Respiratory Infections Caused by Sendai Virus and Influenza Virus

Current understanding of the part played by CD8+ αβ T cells in respiratory virus infections is based on findings from a spectrum of approaches. These include direct analysis of the patterns of lymphocyte involvement in the virus-infected lung (McDermott et al., 1987; Pena-Cruz et al., 1989; Allan et al., 1990; Openshaw, 1991; Eichelberger et al., 1991b), adoptive transfer experiments utilizing either bulk immune T-cell populations or cell lines (Leung and Ada, 1992; Lukacher et al., 1984, 1986; Ada and Jones, 1986; Taylor and Askonas, 1986; Kast et al., 1986; Cannon et al., 1987; Askonas et al., 1988; Mackenzie et al., 1989), in vivo depletion with monoclonal antibody (mAb) (Lightman et al., 1987; Waldmann, 1989; Allan et al., 1990; Eichelberger et al., 1991b), and the use of H-2 mutant or genetically manipulated mice (de Waal et al., 1983; Eichelberger et al., 1991b).