Probing the interactions of NK cell receptors with ligand expressed in trans and cis.

Certain receptors on natural killer (NK) cells, which are specific for MHC class I (MHC-I) molecules, do not only interact with ligand expressed on opposing cell membranes (in trans) but also interact with those on the same cell membrane (in cis). Cis interactions have been demonstrated for only a small number of cell surface receptors. However, this has not been tested systematically, raising the possibility that additional receptors may be able to bind ligand expressed in cis. Here we describe a number of approaches to evaluate trans and cis binding of the Ly49A NK cell receptor to its H-2D(d) ligand. These procedures should facilitate the investigation of cis/trans interactions of other receptor-ligand pairs and simplify the analysis of NK cell receptor variants

The immune response to primary EBV infection: a role for natural killer cells

The role of antigen-specific CD3<sup>+</sup>CD8<sup>+</sup> cytotoxic T cells in the control of primary Epstein–Barr Virus (EBV) infection is well established. However, time is required for the antigen-specific immune response to develop and expand. In contrast, innate immune responses, such as natural killer (NK) cells, are considered vital early in the infection process. We analysed the scale, phenotype and function of the NK cell response during symptomatic primary EBV infection, infectious mononucleosis (IM) and showed that NK cell numbers were significantly elevated both at diagnosis of IM and in the first month following diagnosis. There were also significant changes in cell phenotype and function, an increase in the proportion of CD56<sup>bright</sup> cells at diagnosis, and freshly isolated cells showing an enhanced ability to kill EBV-infected cell lines. Moreover, in our cohort of IM patients higher NK cell counts were associated with significantly lower viral load in peripheral blood. Our results suggest NK cells have an important role in the control of primary EBV infection by eliminating infected B cells and augmenting the antigen-specific T cell response via release of immunomodulatory cytokines. The magnitude of the NK cell response may ultimately determine whether primary EBV infection has a clinical outcome

Mass distribution of hydrodynamic jets produced on the national ignition facility

The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The spatial structure and mass evolution of supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002) and B. E. Blue et. al, Phys. Plasmas 12, 056312 (2005)]. In this paper, the results from the first series of hydrodynamic experiments will be presented in which the mass distribution within the jet was quantified. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the structure of the jet. Comparisons between data and simulations using several codes are presented