We present the case of a 28 year old lady with refractory Crohn's Disease treated with infliximab throughout her pregnancy. Her baby was born healthy and received a Bacillus Calmette-Guérin (BCG) vaccine aged 3 months. Soon after this the infant became unwell and died aged 4.5 months. At post-mortem the cause of death was attributed to an unusual complication of the BCG vaccine, known as disseminated BCG. BCG vaccination is contraindicated in individuals who are receiving immunosuppressive drugs. We recommend physicians should exercise caution before such vaccines are used in infants born to mothers taking anti-TNF therapies or other potentially immunosuppressive IgG1 antibodies.

Inhibition of natural killer (NK) cells is mediated by MHC class I receptors including the killer cell Ig-like receptor (KIR). We demonstrate that HLA-C binding peptides can function as altered peptide ligands for KIR and antagonize the inhibition mediated by KIR2DL2/ KIR2DL3. Antagonistic peptides promote clustering of KIR at the interface of effector and target cells, but do not result in inhibition of NK cells. Our data show that, as for T cells, small changes in the peptide content of MHC class I can regulate NK cell activity.killer cell immunoglobulin-like receptors | MHC class I

In 1989, hepatitis C virus (HCV) was first identified as the infectious agent responsible for human non-A, non-B hepatitis. Two decades later, HCV remains a global public health problem with a suboptimal response rate to treatment and the absence of a protective vaccine. Recent work has highlighted the influence of the innate immune system, and in particular natural killer cells, on the outcome and pathology of HCV infection. These cells are considerably more complex than was originally thought and their role in viral infections is currently being unravelled. This review summarises our emerging understanding of natural killer cells in HCV infection.

SummaryThe key role of natural killer cells in many aspects of the immune response is now being recognized. The last decade has seen an exponential increase in our understanding of the workings of these cells. Receptor diversity is crucial in allowing natural killer cells to respond effectively to a variety of different pathogens. This article reviews aspects of natural killer cell diversity that combine to generate populations of functional natural killer cells that exist within both the individual and throughout the population at large.